19= -2(4 + z) - 3

Somebody pls help :)

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.

The function below show how much jayna and hannah charge for babysitting. which statement best compares the two plants?

Afamily went out to dinner and their bill was $113.if they want to leave a 19% tip, how much should they leave.