First, make up some variables to represent the number of Girls and Boys in the choir.
B = number of boys
G = number of girls
You know that there are 4 times as many girls in the choir as boys. Therefore, the equation you can write is:

If you cross-multiply, then you get the simplified equation:
G = 4B
Intuitively this makes sense since if you multiplied the number of boys in the class by 4, that would be equal to the number of girls you have.
Now, we know that the total class size is 60. So girls plus boys equals 60:
G+B = 60
To solve the equation, replace the G in this equation with the replacement you found before, 4B.
G + B = 60 -->
4B + B = 60 -->
5B = 60 -->
B = 12
However, you are trying to find the number of girls, so plug the answer back into your equation.
G + B = 60 -->
G + 12 = 60 -->
G + 12 -12 = 60 - 12 -->
G = 48
The number of girls you have is 48.
Answer:
<em>Pool 1 leaks faster than pool 2.</em>
Step-by-step explanation:
<u>Rates of change</u>
The rate of change (ROC) is a measure that compares two quantities, usually to know how fast one variable changes in time.
We are given two rates of change for two pools that are leaking. The first one loses 2/3 gallon in 15 minutes, and the other loses 3/4 gallon in 20 minutes.
To compare them, we are required to express time in hours. Recall one hour has 60 minutes, or equivalently, one minute has 1/60 hours. Converting both times, we have:
15 minutes = 15/60 = 1/4 hours
20 minutes = 20/60 = 1/3 hours
Now compute both rates of change:
Pool 1:

Pool 2:

Comparing both ratios, it's clear pool 1 leaks faster than pool 2.
In exponential for it could be 10 raised to the 5th power or 10^5