Answer:
x=10
Step-by-step explanation:
these are similar triangles
8 12
------ = -----------
x+4 2x+1
using cross products
8* (2x+1) = 12(x+4)
distribute
16x + 8 = 12x+48
subtract 12x from each side
16x-12x +8 = 12x-12x+48
4x+8 = 48
subtract 8 from each side
4x+8-8 = 48-8
4x = 40
divide by 4
x=10
