1. sam drove to the beach, 160 miles from his home, at 40 miles per hour. he drove home the next day at 20 miles per hour. calculate the total number of hours that sam spent driving. (hint: distance = rate * time 2. if motocross ace elizabeth bash can travel 110 feet per second on her kawasaki cycle, it would take her seconds for her to travel one mile. hint* there are 5280 feet per mile

Ariana starts with 100 milligrams of a radioactive substance. the amount of the substance decreases by 20% each week for a number of weeks, w. the expression 100(1−0.2)w finds the amount of radioactive substance remaining after w weeks. which statement about this expression is true? a) it is the difference between the initial amount and the percent decrease. b) it is the difference between the initial amount and the decay factor after w weeks. c) it is the initial amount raised to the decay factor after w weeks. d) it is the product of the initial amount and the decay factor after w weeks.