Greetings from Brasil...
According to the statement, one figure is scaled in relation to another, so we can apply similarity to polygons.....
So
BIG/small = BIG/small
or
small/BIG = small/BIG
12.5/10 = X/16
OR
10/12.5 = 16/X
12.5/10 = X/16
10X = 12.5 · 16
X = 200/10
X = 20
