Question

The sum of two numbers is 15. The second number is 1 more than twice the first number

Answer 1

x --- first number

y --- second number

x + y = 2x - 15

x - y = 2y - 5

x - 2x + y = -15

x - y - 2y = - 5

-x + y = -15

x - 3y = - 5

-----------------

-2y = -20 /:(-2)

y = 10

x - 3y = - 5 ⇒ x = - 5 + 3y = - 5 + 3 · 10 = - 5 + 30 = 25

Ans.:

x = 25

y = 10