Cross reference
Numbers 3:46
46 For the redemption of the two hundred seventy-three of the firstborn of the children of Israel, who exceed the number of the Levites,
Exodus 13:13
13 Every firstborn of a donkey you shall redeem with a lamb; and if you will not redeem it, then you shall break its neck; and you shall redeem all the firstborn of man among your sons.
Numbers 18:15-16
15 Everything that opens the womb, of all flesh which they offer to Yahweh, both of man and animal shall be yours: nevertheless the firstborn of man shall you surely redeem, and the firstborn of unclean animals shall you redeem.
16 Those who are to be redeemed of them from a month old shall you redeem, according to your estimation, for the money of five shekels, after the shekel of the sanctuary (the same is twenty gerahs).