You should begin by factorising the numerator and denominator, in order to determine what would go into both parts of the fraction.As you can see, x^{2} and 4x have 'x' in common, and 3x and 12 have '3' in common. Therefore the equation would equal what is shown below.(x^{2} + 3x)/(4x + 12) = (x(x + 3))/(4(x + 3))We see that both parts of the fraction have the common factor of (x + 3), so they cancel each other out.(x~~(x + 3)~~)/(4~~(x + 3)~~)This leaves the fraction fully simplified to x/4.