If a is 60% of b, then what percent of 4a is 5b ?

$$\eqalign{ & a = 60\% {\text{ of }}b \cr & \Rightarrow a = \frac{{60}}{{100}}b \cr & \Rightarrow b = \frac{5}{3}a \cr} $$
∴ Required percentage :
$$\eqalign{ & = \left( {\frac{{5b}}{{4a}} \times 100} \right)\% \cr & = \left( {5 \times \frac{5}{3}a \times \frac{1}{{4a}} \times 100} \right)\% \cr & = \left( {\frac{{625}}{3}} \right)\% \cr} $$