System of equations y=2x+3 y=2x+1

1) you deposit $2,500 in an account that earns 4% simple interest. how much do you earn in eight years?

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?

Which one is the correct answer, and why?