Okay so I'm having a brainfart here. I'm doing a titration problem and have got to the point of:

3.6x10^9 = (.01218-x)/(x)(.00316+x)

I don't know how to proceed from there and use the quadratic formula as silly as it sounds. Any help would be appreciated!

3.6E9*(x)(0.00318+x) = 0.012-x

Clear that and solve.