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 number be 'x'
so,
x=5y, where y is another number.
given that
x+21=2×(y+21)
x+21=2y+42
x=2y+21

we know x=5y
so
5y=2y+21
3y=21
y=21÷3
y=7
so, x=5y=5×7=35
x=35 & y=7