The amount of bending, B mm, of a particular wooden beam under a load is given by B = 0.2m^2 + 0.5m +2.5, where m kg is the mass (or load) on the end of the beam. What mass will produce a bend of 8.8 mm?

I tried to substitute 8.8 for B and then subtracted it from both sides of the equation. After this I tried to use the quadratic formula but was unsuccessful.

Please provide complete working out.