4/(x+1) = 3/x + 1/15
Should we make common denominators with everything, we get
4*15*x / [15x(x+1)] = 3*15*(x+1)/[15x(x+1)] + x(x+1)/[15x(x+1)]
Multiply both sides of the equation by the denominator to cancel them
60x = 45(x+1) + x(x+1)
60x = 45x + 45 + x^2 + x
x^2 - 14x + 45 = 0
(x-9)(x-5) = 0
The answer to this question is that the solutions are x=9 and x=5.