Answer:
x = 16
Step-by-step explanation:
(x +4) : (x +12) :: (x-1)(x +5)
As they are in proportion,
Product of means = Product of extremes
(x + 4)* (x +5) = (x + 12)(x - 1) {Use FOIL method}
x*x +x*5 +4*x + 4*5 = x *x + x*(-1) +12*x + 12*(-1)
x² + 5x + 4x + 20 = x² - x +12x - 12 {Now combine like terms}
x² + 9x + 20 = x² + 11x -12
x² + 9x +20 - x² - 11x = -12
x² - x² + 9x - 11x = -12 - 20
0 - 2x = - 32
-2x = -32 {Divide both sides by -2}
x = -32/-2
x = 16
