Answer:
x = 8
Step-by-step explanation:
small triangle is similar to larger one
set up a proportion: 9 = x + 4
9+12 x+4+2x
9 = x+ 4 cross-multiply: 9(3x + 4) = 21(x + 4)
21 3x + 4 27x + 36 = 21x + 84
6x + 36 = 84
6x = 48
