Question:
Tick (✓) the correct answer
A number decreased by $27 \frac{1}{2} \%$ gives 87 . The number is
(a) 58
(b) 110
(c) 120
(d) 135
Solution:
(c) 120
Let the required number be $\mathrm{x}$. Then, we have:
$x-\left(27 \frac{1}{2} \%\right.$ of $\left.x\right)=87$
$\Rightarrow \mathrm{x}-\left(\frac{55}{2} \%\right.$ of $\left.\mathrm{x}\right)=87$
$\Rightarrow \mathrm{x}-\left(\mathrm{x} \times \frac{55}{2} \times \frac{1}{100}\right)=87$
$\Rightarrow \mathrm{x}-\frac{11 \mathrm{x}}{40}=87$
$\Rightarrow \frac{29 \mathrm{x}}{40}=87$
$\Rightarrow \mathrm{x}=\left(87 \times \frac{40}{29}\right)$
$\Rightarrow \mathrm{x}=120$