If a number is reduced by 40% it becomes two-thirds of another number. What is the ratio of the first number to the second number ?

Answer: Option C

Let the numbers be $$x$$ and $$y$$ respectively
Then,
60% of $$x$$ = $$\frac{2}{3}$$ $$y$$
⇒ $$\frac{60}{100}$$ $$x$$ = $$\frac{2}{3}$$ $$y$$
⇒ $$\frac{3}{5}$$ $$x$$ = $$\frac{2}{3}$$ $$y$$
⇒ $$\frac{x}{y}$$ = $$\frac{2}{3}$$ × $$\frac{5}{3}$$
⇒ $$\frac{x}{y}$$ = $$\frac{10}{9}$$
∴ x : y = 10 : 9