Question

A number is decreased by 15 and the new number so obtained is multiplied by 3; the result is 81. Find the number. [3 MARKS]

Answer 1

Equation: 1 Mark
Steps: 1 Mark
Answer: 1 Mark

Let the number be $x$.

The number decreased by 15 $\Rightarrow (x-15)$

The number so obtained is multip[lied by 3 $\Rightarrow 3\times (x-15)$

Given: $3(x-15)=81\Rightarrow 3x-45=81$

$\Rightarrow 3x=81+45$

$\Rightarrow x=\frac{126}{3}=42$

$\therefore$ The required number = $42$