Let the required ratio be x : y. Then, \(\frac{15X}{100}\) + \(\frac{40y}{100}\) = \(\frac{30(X+y)}{100}\)
\(\therefore\) 15x + 40y = 30x + 30y
\(\Rightarrow\) 10y = 15x \(\Rightarrow\) \(\frac{X}{y}\)= \(\frac{10}{15}\) = \(\frac{2}{3}\) \(\Rightarrow\) x : y = 2 : 3.