How was the price of redemption for an unclean firstborn animal determined?
Leviticus 27:27 (ESV)
27And if it is an unclean animal, then he shall buy it back at the valuation, and add a fifth to it; or, if it is not redeemed, it shall be sold at the valuation.
The price of redemption was determined by the priest. Additionally, a fifth of its value was added to the cost.
27 And if it is an unclean animal, then he shall buy it back at the valuation, and add a fifth to it; or, if it is not redeemed, it shall be sold at the valuation.