Mr. pham wrote the equation below on the board. 18 - 7x = -20.5 what is the value of x?

Use the arithmetic operations to get the variable x on one side of the equation and everything else on the opposite side.

If something is being is being done to a variable, we undo that operation by using the inverse of that operation.

For example, if 10 is being added to x, we use the inverse of addition or subtraction.

18 - 7x = -20.5

We variable x is being multiplied by 7 and is subtracting 18. We need to undo all those operations.

18 - 7x = -20.5
-7x = -38.5

Now the variable is only being multiplied by -7. Reverse the operation.

-7x = -38.5
x = 5.5

So, x is equal to 5.5.