Question

A positive number is 5 times another number. If 21 is added to both the numbers ,then one of the new number become the twice of new number. What is the number.

Answer 1

let the smaller number = x
bigger number = 5x. -----(we need this.)

if 21 is added to both; 5x+21 = 2×(x+21)

5x + 21 = 2x + 42

5x - 2x = 42 - 21

3x =. 21

x = 21/3= 7

So the positive number is = 5×7 = 35

answer is 35

Answer 2

Hey


x = 5y

x + 21 = 2( y +21)

x + 21 = 2y + 42

Substitute the first equation in the second one,

5y + 21 = 2y + 42

5y + 21 - 2y - 42 = 0

3y -21 = 0

3y = 21

y = 21/3 = 7

x = 5y


Therefore, x = 5 * 7

x = 35



The number is 35.


Hope this helps