Write a system of equations:
x + y = 125
20x + 15y = 2100
Solving:
x = 125 - y
20(125 - y) + 15y = 2100
2500 - 20y + 15y = 2100
2500 - 5y = 2100
-5y = 2100 - 2500
-5y = -400
y=80
x + 80 = 125
x = 125 - 80
x = 45
The first charges 45$ per hour and the second charges 80$ per hour
You can use calculus ( related rates). Given the rate os change of the radius for example you can find the rate of change of volume using differential calculus.
The answer is -11 and -13
Do you know What topic this is ?
Answer: 
Step-by-step explanation:
Given :
add 2 to both sides
Therefore :
