I need emergency help if you help I’ll be soo happy :) plsss

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.

At your job you're paid $50 per week plus $3 per sale at least how many saled do you need to make in order to have over $250

When steve woke up. his temperature was 102 degrees f. two hours later it was 3 degrees lower. what was his temperature then?