Arrange the equations so they are in the point-intercept form y = mx + b. Move the term with the x-variable and the constant over on the right hand side and divide by the coefficient in front of the y.
Write down the first equation on a piece of paper. Write the second equation directly underneath it. Align the two functions so their y's, x's and constants are directly under one another.
Subtract the second equation from the first one. You can write a big subtraction sign in front of the equation and distribute it through when you do the subtraction. Because you divided by the y-coefficient in Step 1, you will get a y-y = 0 on the left-hand side.
Write down the new equation from Step 4. It will be in the form 0 = mx + b. Solve for "x" by subtracting the "b" and dividing by the slope on both sides.
Plug the x-value from Step 6 into the resultant equation from Step 4 and solve for the surface area "y."