The world's population went from 3 billion in 1960 to 6 billion in 2000. Suppose the world population continued to grow from 2000 on with a doubling time of 40 years. What would the population (in billions) be in 2030? Round to the nearest hundreth​

Solve the equation -9p - 17 =10 a -3 b. 16 c. 18 d -16

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.

Ijust need these 2 questions answered (the second pic is just confirmation i'm not confident in that answer)