Answer:
D. b=15 and a=7
Explanation:
compare the left triangle to the right triangle by looking at the short sides
How do we get from 9 to 3?
setting an equation
9x = 3
divide both sides by 9
x = 3/9 simplified to 1/3
The scale factor is 1/3
so a is:
21 × 1/3 = 7
b is:
5 ÷ 1/3 = 15