Jennifer and margaret have to make brownies for a bake sale. jennifer can bake a dozen brownies in 20 minutes and margaret can bake 15 brownies every half hour. jennifer bakes for 1 hour and 40 minutes and margaret bakes for 2 hours. how many brownies do the girls have for the sale altogether?

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.