Write an Equation and Solve. Put your answer, not the equation. in the blank. 1. The sum of a number n and negative 12 is 6.

2. 45 equals the quotient of a number n and 3.

3. 30 less than a number n is 10.

4. 5 less than twice a number n is negative 25.

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.