Which equation is an example of the commutative property of multiplication?
(4 +21) = (21 + 4)
(4 + 21) (3 - 51) = (3-51)(4 + 21)
(4 + 21(3-5) = (4 + 21(3 - 5)(1)
(4 + 21) = (4 + 2i + 0)

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?