Based on the given triangle, you can notice that the base and height of the triangle A is:
b = 3
h = 3
By using the formula for the area of a triangle you have:
A = b*h/2 = (3)(3)/2 = 9/2 = 4.5
a. The scaled triangle is 72, then, you have:
72/4.5 = 16
The scaled triangle is 16 times larger than triangle A.
b. The scale factor is 16
c. The length of the bottom side is:
b*16 = 3*16 = 48