Answer:
84
Step-by-step explanation:
f(1)=4^1 - 1 = 3
f(4) = 4^4 - 1 = 255
rate of change = 
(255 - 3) / (4 - 1) = 252 / 3 = 84
Answer:
One month of gameplay costs $15
Step-by-step explanation:
Angie: 20 + 3x
Kenny: 20 + 2x
(20 + 3x) + (20 + 2x) = 115 --- add their costs together
(20 + 20) + (3x + 2x) = 115 --- collect like terms
40 + 5x = 115 --- simplify
5x = 75 --- subtract 40 from both sides
x = 15 --- divide both sides by 5
The answer would be 50 and 37.
50-37 = 13
50+37 = 87