If 60% A = $$\frac{3}{4}$$ of B, n A : B is

$$\eqalign{ & {\text{60}}\% \,{\text{of}}\,{\text{A}} = \frac{{\text{3}}}{{\text{4}}}\,{\text{of}}\,{\text{ B}} \cr & \Rightarrow \frac{{60}}{{100}}{\text{A}} = \frac{3}{4}\,{\text{B}} \cr & \Rightarrow \frac{{\text{3}}}{{\text{5}}}{\text{A = }}\frac{{\text{3}}}{{\text{4}}}\,{\text{B}} \cr & \Rightarrow \frac{{\text{A}}}{{\text{B}}}{\text{ = }}\frac{{\text{3}}}{{\text{4}}} \times \frac{{\text{5}}}{{\text{3}}} \cr & \Rightarrow \frac{{\text{A}}}{{\text{B}}} = \frac{5}{4} \cr} $$
⇒ A : B = 5 : 4