Finding common denominators allows you to more easily get your answer for the problem. fractions are complex as it is if you have a denominator of 16 and 4 your immediate reaction would be to just subtract the process and answer would be completely wrong.
Your answers will be:
x= 0.44
and
x= -1.84
F(x) = x(x -1)
f(3) = 3*2 = 6
f(6) = 6*5 = 30
so f(f(3)) = 30 . . . . . selection A
