Question 51696
Your answer is correct:
5(3 - 2x) = 4(4x + 20) or 
15 - 10x = 16x + 80 or 
-65 = 26x or 
x = -65/26 
x=-2.5 [Decimal form is easier to check]

.

and then to proof 
5(3 - 2(-2.5)) = 4(4(-2.5)+ 20) [Check by plugging -2.5 back into the equation]
40=40 [Checks out]