Question

Point E is between points D and F. If DE = x - 4 , EF = 2x + 5 , and DF = 4x- 8 , find x

Answer 1

You know that 
$DE+EF=DF (x-4) + (2x+5) = (4x-8)$

combine like terms$3x+1 = 4x-8 1 = x-8 x=9$