How do you solve for x in this case?

x=12

Step-by-step explanation:

since the triangles are similar their sides are in proportion

50/40 = ( -6+3x) / 24; multiply both sides by 24

50 * 24 / 40 = -6 +3x; simplify the fraction

30 = -6 +3x; add 6 on both sides

30+6 = 3x; add and divide both sides by 3

36/ 3 = x

12 =x

the x is 12

the side is -6 +3*12