Fossils are often dated using the differential equation dA dt = A, where A is the amount

Fossils are often dated using the differential equation dA dt = −αA, where A is the amount of radioactive substance remaining, α is a constant, and t is measured in years. Assuming that α = 1.5×10−7, determine the age 1.6. Exercises 37 of a fossil containing radioactive substance A if only 30% of the substance remains.