Pls answer correctly c:

The parabola y = x² - 4 opens: a.) up b.) down c.) right d.) left

Can someone me and do the problem plz so i can understand it more better

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?