Through using the pythagorean theorem, you should find the hypotenuse of the smaller triangle to be 10 units. Therefore, the perimeter of the smaller triangle is 6+8+10 = 24 units.
The perimeter of the larger triangle is 60 units. The ratio here is 24:60 = 2:5
Meaning that the larger perimeter is 5/2 = 2.5 times that of the smaller.
We apply this scale factor 2.5 to the smaller hypotenuse 10 to jump to 2.5*10 = 25, which is the length of the larger hypotenuse.
