By what percentage do you reduce 6.25" x 10.00" to arrive at 4.25" x 7.12"?

Question

Trying to use a printer to reduce a photo to fit the cover of a book

Answer 1

if the original 10" dimension becomes 7.12", then it has been multiplied by 0.712, which means that 1 - 0.712 is the amount lost; that's 28.8% reduction

I leave it to you to determine if that same % reduction was applied to the other measurement.