There may be an easier way, but here goes:

Starting with

Divide through by , and rearrange:

This factors out to the form:

(eqn 1)

Where and . You have two equations in two unknowns, which gets you to:

Use the quadratic formula to solve for A:

1.448 or 11.052, B = 12.5-A = 11.052 or 1.448

Put these values back into the equation (1):

So:

or: