Answer:
5(2x-8)+15=-15
10x-40+15=-15
10x-25=-15
+25 +25 (add 25 to both sides)
____________
10x=10
divide by 10 on both sides
x=1
Answer:
y = 5 e^r * t
Let y be the population in billions and t the value of elapsed years
7 = 5 e^r * t is the equation being used where t = 15
7/5 = e^r * t
ln 7/5 = r * t taking ln of both sides
r = .336 / 15 = .0224
y = 5 e^(.0224 t) is then our equation
Check - suppose you want y at 2020
y = 5 e^(.0224 * 20) would be the equation
y = 5 e^.449 = 7.83 billion - seems to be a reasonable answer
When you simplify the expression you get 38. Hope this helps.
Answer = 38.
