New Revised Standard Version
If it is an unclean animal, it shall be ransomed at its assessment, with one-fifth added; if it is not redeemed, it shall be sold at its assessment.

Contemporary English Version
If you promise me a donkey, you may buy it back by adding an additional 20 percent to its value. If you don't buy it back, it can be sold to someone else for whatever a priest has said it is worth.

New American Bible
But if it is an unclean animal, it may be redeemed by paying one fifth more than its value. If it is not redeemed, it shall be sold at its value.

Douay-Rheims Bible
And if it be an unclean beast, he that offereth it shall redeem it, according to thy estimation, and shall add the fifth part of the price. If he will not redeem it, it shall be sold to another for how much soever it was estimated by thee.

And if it be an unclean beast, he that offereth it shall redeem it, according to thy estimation, and shall add the fifth part of the price. If he will not redeem it, it shall be sold to another for how much soever it was estimated by thee.

and shall add.

Leviticus 27:11-13 An unclean beast, which cannot be sacrificed to the Lord, if any man shall vow, shall be brought before the priest: . . .