5. The difference between $\frac{1}{3}$ of a certain number and $\frac{1}{4}$ of the same number is 3 . What is that number?
A 24
B 36
C 48
D 60
E 72
5. B Let the required number be $x$. Then $\frac{x}{3}-\frac{x}{4}=3$. Multiplying both sides by 12 gives $4 x-3 x=36$. So $x=36$.