71 B. Jacob (Exodus, 287) shows that the intent of Moses in using גַּם (gam) is to make an emphatic rhetorical question. He cites other samples of the usage in Num 22:33; 1 Sam 17:36; 2 Sam 12:14, and others. The point is that if Pharaoh told them to go and serve Yahweh, they had to have animals to sacrifice. If Pharaoh was holding the animals back, he would have to make some provision.
72 Heb “give into our hand.”
73 The form here is וְעָשִּׂינוּ (vé’asinu), the Qal perfect with a vav (ו) consecutive—“and we will do.” But the verb means “do” in the sacrificial sense—prepare them, offer them. The verb form is to be subordinated here to form a purpose or result clause.

In other versions

But Moses said, “You must also let us have sacrifices and burnt offerings, that we may sacrifice to the Lord our God.

But Moses said, “You must allow us to have sacrifices and burnt offerings to present to the Lord our God.

Moses responded, “You must also let us have sacrifices and burnt offerings to prepare for the Lord our God.

“No,” Moses said, “you must provide us with animals for sacrifices and burnt offerings to the Lord our God.

And Moses said, “Even if you yourself put into our hand sacrifices and burnt offerings and we offer them to Yahweh our God,

And Moses said, Thou must give us also sacrifices and burnt offerings, that we may sacrifice unto the Lord our God.

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