Yes, I knew at least that much, but how did they go further after that and get rid of the coefficients in the numerators? It couldn't have been just from dividing them out because the other terms of the equations don't look like they've been divided by them. The fractions in the denominators seem strange to me.
EDIT: Ah, nevermind, after re-writing the terms as division problems, it returns back to that form you wrote.