Can someone please help me​

The perimeter of a movie screen is 54 meters. the screen is 18 meters wide. how tall is it?

Write the expression 7x^3-28xy^2 as the product of 3 factors

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?