I've already found the solution using an online calculator, but I'm wondering if one of you is able to work it out by hand and show me the steps: A: p + r = 6; B: pr + q + s = 16; C: ps + qr = 22; D: qs = 15. The solution is: p=2, q=3, r=4, s=5. I've tried the following steps: First, solve A for p in terms of r: p = -r + 6. Then, solve D for s in terms of q: s = 15/q. Next, I plugged those into B like so: (-r + 6)r + q + 15/q = 16. Then, I solved that new equation for r in terms of q and got the following: r = [3q +- sqrt[q(-q^2+25q-15)]] / q. Finally, I tried subbing everything into equation C (including that long, hairy expression for r) and solving for q. After several pages of meticulous algebraic manipulation, it seems like a wild goose chase. Perhaps there's a better approach? Thanks for any help.