please answer fast!

1. A car worths $70 000 now and its value depreciates at a constant rate of 15% per year. Find the minimum number of years for the value of the car to depreciate to less than $36 600. [5 marks] 2. The weight (Wkg) of a decaying radioactive substance after t years is given by W = W. ( ) 100 ,where W. kg is the initial weight of the substance. (a) Find the number of years for the radioactive substance to decay to half of its initial weight. ( b ) At least how many years will it take for the radioactive substance to lose to 10% of its initial weight? [7 marks] P. 11 of 12