When we look at this thing for the first time, it looks like it's going to be a dog of a bear to solve, because 'q' is buried inside a squared term and a cubed term.
But this is why it's so important to learn that in math, you DON't immediately ignite your hair and go running around in circles as soon as you see the problem. The first thing you have to do <u>every</u> time is sit still, look at the problem, breathe air, and switch your brain into the 'ON' position.
Look at that big ugly fraction in the equation. Can it be simplified ? You betcha it can ! The quantity (q+r) is a factor of the numerator and denominator, so we can do some canceling.
Divide the top and the bottom of the fraction by (q+r)², and then the problem says . . .
<em>p = (q+r)/12 + 4r</em>
which is MUCH easier to unravel and solve for 'q' . Let's do this !
p = (q+r)/12 + 4r
Subtract (q+r)/12 from each side . . . p - (q+r)/12 = 4r
Subtract 'p' from each side . . . -(q+r)/12 = 4r - p
Multiply each side by -1 . . . (q+r)/12 = p - 4r
Multiply each side by 12 . . . (q+r) = 12p - 48r
Subtract 'r' from each side . . . <em>q = 12p - 49r</em>
