Abigail's toaster produces 50 units of heat and 5 units of light for every 100 units of electricity it uses. What is the efficiency of her toaster? 5 percent 45 percent 50 percent 55 percent

45 percent because it's purpose is not to make light, but heat. Since that is excess wasted energy, you would subtract the wasted energy from the units of energy used for the desired task (50-5) and it would give you 45