18. 5-2x = -4x+9 2x = 4 x = 2 perimeter = length of one side x 3 perimeter = [5-2(2)] x 3 = 3
19. 3(x-1) = 5x-6 3x-3 = 5x-6 -2x = -3 x = 1.5 perimeter = [3(1.5-1)] x 5 =7.5
20. 4/3x-⅓ = x+7 4x-1 = 3x+21 (multiply throughout by 3 to get rid of denominator on LHS) x = 22 perimeter = (22+7) x 6 = 29 x 6 = 174 ^ not sure about qn20 because i can’t tell if it’s x+7 or x divided by 7 it’s kinda blurry
