Hi plz help very tired

Using elimination, what is -4x+2y=-12 4x+8y=-24

Ascientist has 50 grams of a radioactive element. the amount of radioactive element remaining after t days can be determined using the equation (1) after two days the scientist receives a second shipment of 50 grams of the same element. the equation used to represent the amount of shipment 2 remaining after t days is 10) - 50 which of the following is an equivalent form of the expression for the amount remaining in shipment 2? what’s the answer?

Awindow washer cleans 42 windows in 2 hours. at this rate, how many windows did he clean in 180 minutes.