Just do 10 dived by 4, which is 2.5
It has been dilated by 2.5.
If you want to be sure just do 20 divided by 8 which is also 2.5 and 25 divided by 10 which is 2.5 and 12.5 divided by 5 which is 2.5.
Basically, all you have to do to figure it out is take the bigger number and divide it by its matching side
