Question

A positive number is $5$ times another number. If $21$ is added to both the numbers, then one of the new numbers becomes twice the other new number. What are the numbers?

Answer 1

Let the positive number be $x$

Then another number will be $5x$

According to the question if $21$ is added to both the number.

$\Rightarrow 5x+21=2(x+21)$

$\Rightarrow 5x+21=2x+42$

$\Rightarrow 5x-2x=42-21$

$\Rightarrow 3x=21$

$\Rightarrow x=\frac{21}{3}$

$\Rightarrow x=7$

Hence, the number is $x=7$

the other number is $5x=5\times 7$

$=35$