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 two numbers be x &y respectively
let x=5y
x+21=y+21
given that,
5y+21=2(y+21)
⇒3y-21=0
   3y=21
     y=7 and x=35
check:
       if y=7 then,x=5*7=35
       35+21=2(7+21)=56

Answer 2

Let one number be x
and other number is 5x
If 21 is added
then one number =x+21
and other number =5x+21
A/q
(x+21)=2(5x+21)
=>x+21=10x+42
=>10x-x+42-21=0
=>9x+21=0
=>3(x+7)=0
=>x+7=0
=>x=-7

Therefore,
One number is =7
and another number is 5×7=35.