Question

Mark the correct alternative in the following question:

Twice a number when increased by 7 gives 25. The number is

(a) 7 (b) 9 (c) 10 (d) 8

Answer 1

$$\begin{gathered} \mathrm{Let}\mathrm{the}\mathrm{number}\mathrm{be}x. \\ \mathrm{As},\mathrm{twice}\mathrm{the}\mathrm{number}\mathrm{when}\mathrm{increased}\mathrm{by}7\mathrm{gives}25. \\ \Rightarrow 2x+7=25 \\ \Rightarrow 2x=25-7\left(\mathrm{By}\mathrm{transposing}7\mathrm{to}\mathrm{RHS}\right) \\ \Rightarrow 2x=18 \\ \Rightarrow x=\frac{18}{2}\left(\mathrm{By}\mathrm{transposing}2\mathrm{to}\mathrm{RHS}\right) \\ \therefore x=9 \end{gathered}$$

So, the number is 9.

Hence, the correct alternative is option (b).