triangle Area = .5 * (base * height)
36 = (base * height) / 2
So let's say base = 9 height 8
If base and height are scaled by a factor if 5 than
base = 45 height 40 and
area = .5 * (45 * 40)
area = 900
Basically, the area increases by a factor of 25.
The base increases by 5 and the height increases by 5 so the area increases by 5*5 = 25
