Answer:
x=19.5 or 19 1/2
Explanation:
To find what x is we need to get x on one side of the equal sign with the numbers on the other side, but first, we need to add the same variables and numbers together.
Add:
4x+12=90
Move the 12 to the other side by subtracting 12 on both sides (You use the inverse of what you want to move to the other side)
4x+12-12=90-12
4x=78
Divide:
You need to divide 4x by 4 (Since 4x is the same thing as 4*x you need the inverse of multiplication to reverse it which is division)
x=19.5 or 19 1/2 (Since 1/2 is the same thing as 0.5)