Question

Create an equation with one solution of x = −7.

10x − (x − 2) = 2x − (_+ x)
Full question is on attached image. All help is appreciated :)

Answer 1

10x − (x − 2) = 2x − (40 + x).

The missing number is 40.

Explanation:

Let the missing number be a, Then:

10x - (x - 2) = 2x - (a + x)

10x - x + 2 = 2x - a + x

9x - 2x - x = -a - 2

6x = -a - 2

When x = -7:

6(-7) = - a - 2

-42 + 2 = -a

-40 = -a

a = 40.

So the equation is

10x − (x − 2) = 2x − (40 + x).