xy = 12 ---------- eq (i)
x + y = 7_____x = 7 - y -------- eq (ii)
y(7 - y) = 12 ---- Substituting 7 - y for x in eq (i)
(y - 4)(y - 3) = 0
Now substitute each y value into any of the 2 original equations to determine the 2 corresponding values of x.
You'll see that the following solutions are derived: