1) get rid of the square root by squaring both sides of the equation
2) multiply the x * 8.8 * x together to get 8.8x^2
3) your equation should now look like
8.5^2 = 8.8x^2 (the only difference is that you would have solved out 8.5^2)
4) divide 8.8 to the other side to single out the x's
5) square root both sides to get rid of the square on x
6) you answer should be
x = {square root of [(8.5^2)/(8.8)]}