Leviticus 7:12

If he offer it for a thanksgiving let him offer with the oblation of thanks unleavened cakes mingled with olive oil, and unleavened wafers anointed with olive oil, and flour fried with a mixture of olive oil.

if he offers it for thanksgiving i.e., he gives thanks to God for having escaped a difficulty.

maṣṣa cakes [plural] and also maṣṣa wafers [plural] as many as he desires, but not fewer than two.

fine flour the interpretations that I prefer render the adjective as “preferred”. The maṣṣa cakes and the maṣṣa wafers are baked; the breads of fine flour are not.

THEN HE SHALL OFFER ‘AL’ THE OFFERING OF THANKSGIVING. The commentators have explained the word al as meaning “with” — with the offering of thanksgiving. Similarly, ‘al’ the cakes of leavened bread means “with them.” The correct interpretation appears to me that the word al is here to be understood in its ordinary sense [i.e., “upon”], meaning that he should add bread “upon” the offering. Similarly, ‘al’ the cakes of leavened bread he shall present his offering, means that he is to bring cakes of leavened bread, and adding “upon” them he is to bring his offering, which is the unleavened bread mentioned [in Verse 12 before us] — all these breads [thirty unleavened cakes and ten leavened ones] he is to bring upon the offering [of thanksgiving]. Scripture thus made the leavened bread the chief part of the offering, “adding” upon it the rest of the bread [i.e., the unleavened bread, by stating “upon the cakes of leavened bread he shall present his offering,” which means “his unleavened bread”], because the unleavened breads are more than all the other kinds. Scripture changed the expression, stating, [he shall present his offering] of his peace-offerings for thanksgiving [while here in Verse 12 it merely says, the offering of thanksgiving], in order to allude to the Rabbis’ interpretation regarding it, namely that the bread does not become holy in itself [in the sense that it cannot be redeemed, or that it becomes invalid if carried outside the wall of the city, etc.] until the offering is slaughtered, and [also] that it should be slaughtered “upon” it [the bread], that is to say, with the intention that the bread should become holy with it [the offering].
Now Rashi wrote: “Then he shall bring with the offering of thanksgiving four sorts of bread: cakes, wafers, and cakes mingled with oil — these three kinds being of unleavened bread. And it further states, with cakes of leavened bread, [thus making four kinds], and each kind consisted of ten cakes. Thus it is explained in Tractate Menachoth. And their total measure was five Jerusalem seahs, which are six measures according to the Wilderness measure, or twenty tenths [of the ephah].” Now the Rabbi [Rashi] did not mention in connection with these twenty tenths [of flour] that ten of them were for the leavened cakes, a tenth for each one, and the other ten tenths for the unleavened ones, thus making three unleavened cakes to each tenth of flour. The Rabbis interpreted that this is so on the basis of the verse, ‘al’ cakes of leavened bread, [which they explained as meaning]: “‘Corresponding to’ [the amount of flour used in the preparation of the ten] leavened cakes, use the same amount to bring therefrom [the thirty] unleavened cakes. Thus there were twenty tenths [of an ephah of flour], ten for the leavened cakes and ten for the unleavened. Ten tenths were used for the leavened ones, thus making one tenth of flour for each of [the ten] leavened cakes, and ten tenths for the unleavened ones, thus making three cakes to one tenth of flour. Thus there were forty cakes altogether.”

אם על תודה, if a person had made a vow using the expression תודה instead of using the expression שלמים to describe what he vowed to bring. The most common occasion when people make such a vow is when they have been saved from imminent danger. The sages in Berachot 54 described the four types of dangers which qualify for the party who has been saved to offer such a “thanksgiving” offering, תודה. The total number of challot which this offering consists of are 40. Here we are told all the details.