Question

What makes the value of x makes the equation true?

`7x = 80 + 9x`
​

Answer 1

`x=-40`

Explanation:

You need to find the value of x. To do this, you need to isolate the variable:

`7x=80+9x`

Move the 80 to the left side of the equation using the reverse operation of '+', which is subtraction:

`7x-80=80-80+9x\\\\7x-80=9x`

Now move the coefficient, 7x, to the right side of the equation using the reverse operation of addition (because it's a positive number), which is subtraction:

`7x-7x-80=9x-7x\\\\-80=2x`

Now isolate the variable using reverse operations. The coefficient can also be seen as
`2*x` , so the opposite of multiplication is division. Divide by 2, remembering to do the same on both sides of the equation to keep it stable:

`-(80)/(2)=(2x)/(2)\\\\ -40=x`

The value of x is -40.

:Done