Question

Mark the correct alternative in the following question:

The sum of two consecutive whole numbers is 43. The smaller number is

(a) 21 (b) 22 (c) 23 (d) 24

Answer 1

$$\begin{gathered} \mathrm{Let}\mathrm{the}\mathrm{two}\mathrm{consecutive}\mathrm{whole}\mathrm{numbers}\mathrm{be}x\mathrm{and}x+1. \\ \mathrm{As},\mathrm{the}\mathrm{sum}\mathrm{of}\mathrm{the}\mathrm{two}\mathrm{consecutive}\mathrm{whole}\mathrm{numbers}\mathrm{is}43. \\ \Rightarrow x+\left(x+1\right)=43 \\ \Rightarrow 2x+1=43 \\ \Rightarrow 2x=43-1\left(\mathrm{By}\mathrm{transposing}1\mathrm{to}\mathrm{RHS}\right) \\ \Rightarrow 2x=42 \\ \Rightarrow x=\frac{42}{2}\left(\mathrm{By}\mathrm{transposing}2\mathrm{to}\mathrm{RHS}\right) \\ \therefore x=21 \end{gathered}$$

So, the smaller number is 21.

Hence, the correct alternative is option (a).