SSC CHSL 4 Mar 2018 Shift 3 Paper

Ratio of first number to second number = 3 : 5 and ratio of the second number to the third number = 4 : 7
Multiplying first equation by 4 and second equation by 5 to make the second (common) term equal.
Let first number be = $2\mathit{x}$ , second number = $20\mathit{x}$ and third number = $35\mathit{x}$
⇒ Sum = $12\mathit{x}+20\mathit{x}+35\mathit{x}=67\mathit{x}=67$
⇒ $\mathit{x}=\frac{67}{67}=1$
∴ Second number = $20\times 1=20$