Find the volume v of the solid obtained by rotating the region bounded by the given curves about the specified line. y = 3 4 x2, y = 7 4 − x2; about the x-axis

When you are solving this equation you want to add 3 to both sides because that is the inverse of subtracting 3. The reason you do it to both sides is because you want to balance the equation. After you do this the equation will be -2x=-4. Now you would divide by -2 on both side because x is being multiplied by -2, and the inverse of multiplication is division so:
x = 2.