Question

The sum of two numbers is 40. The second number is 5 less than twice the first number. Let x represent the first number and let y represent the second number. What is the value of the first number? Use the table to guess and check.

Answer 1

Explanation:

x+y=40

y=2x-5

`x = 40 - y \\ y = 2(40 - y) -5 \\ y = 80 - 2y - 5 \\ 3y = 75 \\ y =25 \\ x = 40 - y \\ x = 15`