Find the value of a and b

What is the product? a-3/15a × 5/a-3

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?

There are 93 calories in a small candy bar how many calories are ther in a half dozen small candy bars?