Question

Fifteen more than half a number is 9

Answer 1

For this case, the first thing we must do is define a variable.

We have then:

x: unknown number

We now write the equation that models the problem:

$(\frac{1}{2}) x + 15 = 9$

From here, we clear the value of x.

We multiply both sides of the equation by 2:

$(\frac{2}{2}) x + 2 (15) = 2 (9)\\x + 30 = 18$

We subtract 30 on both sides of the equation:

$x + 30 - 30 = 18 - 30\\x = -12$

Answer:

The value of the unknown number is given by:

$x = -12$

Answer 2

$x-\ number\\\\ \frac{1}{2}x+15=9\ \ \ \ | subtract\ 15\\\\ \frac{1}{2}x=-6\ \ \ | multiply\ by\ 2\\\\ x=-12\\\\Number\ is\ -12.$