Question

Half a number plus 2.5 times that number equals 18. What is the number?

Answer 1

The number is `6`

Explanation:

Use a variable to define the number.
Let the number be `x`

Write an expression for each phrase referring to our number.

"half the number" means the number divided by 2: `1/2x or x/2`
"2.5 times the number " means `2.5xx x = 2.5x`
(`2.5x " is the same as " 2 1/2x`)

When we add them together we get 18.

`1/2x + 2 1/2x = 18`

`3x = 18`

`x = 6`