A 75-W, 120-V bulb is connected in parallel with 25-W, 120-V bulb. What is the net resistance?

Answer 1

P = 75 + 25 = 100 W., Total.

P = 120 * I = 100
I = 100/120 = 0.833A

R = E/I = 120/0.83333 = 144 Ohms.