If q*r = 13 and p*t = 8 and we want to find q*t, then we must solve for q and t before multiplying them together.
We can divide qr = 13 by r to solve for q.
q = 13/r
We can divide pt = 8 by p to solve for t
t = 8/p
We multiply both of those equations together to get our answer.
q*t = (13/r)*(8/p) = 104/rp
