There are three sources of resistance in a parallel circuit Two of them are rated at 20 ohms the other at 10 ohms What is the circuit's total resistance?

Well, honey, in a parallel circuit, you can't just add up the resistances like you're at a buffet. You gotta use the formula 1/Rtotal = 1/R1 + 1/R2 + 1/R3. Plug in the values and you'll find the total resistance is 6.67 ohms. So, grab your calculator and get to work, darling.