Question

The second of two numbers is five more than twice the first. There sum is 80 . Find the numbers.

Answer 1

x = first number

y = second number

1. y = 2x +5

2. x = x

3. x + 2x + 5 = 80

4. 3x +5 = 80

5. 3x = 75

x = 25

sub back in to steps 1 and 2:

x = 25

y = 2(25) + 5

y = 55

the first number is 25, and the second number is 55.

CHECK:

80 - 25 = 55

Explanation:

1. define your variables

2. use the question to find what each number equals

3. set them equal to 80

4. combine like terms, divide, etc. (SOLVE)

5. sub back into defined variables.

6. check it by subtracting and adding

Answer 2

The first number = x

The second number = 5 + 2x

80 = x + 5 + 2x

Let's combine like terms.

80 = 3x + 5

Subtract 5 from both sides.

75 = 3x

Divide both sides by 3

25 = x

The first number = 25

Let's plug 25 into x for our second number's equation.

The second number = 5 + 2(25) = 55