FullSimplify [ (1/ 2 (3 l* (3 l/2*Sqrt [3])))/ ( (3 (1/2 (l* (l/2*Sqrt [3])))) + (1/ 2 (3 l* (3 l/2*Sqrt [3])))), TransformationFunctions -> {Sow, Automatic}] // Reap. Which just gives the answer of 3/4ths
Solve NowTry entering the problem into WolframAlpha. For example you can see where both sides of the equation are equal: T he pro version typically shows the steps you'd use to derive the results