Answer:
Step-by-step explanation:
An exponential function is of the form

where a is the initial value and b is the growth/decay rate. Our initial value is 64. That's easy to plug in. It goes in for a. So the first choice is out. Considering b now...
If the rate is decreasing at .5% per week, this means it still retains a rate of
100% - .5% = 99.5%
which is .995 in decimal form.
b is a rate of decay when it is greater than 0 but less than 1; b is a growth rate when it is greater than 1. .995 is less than 1 so it is a rate of decay. The exponential function is, in terms of t,

The equation is 
The solved equation is 11
First, we must add 13 on both sides

The answer to the equation is 
Answer: 6.7*10^-5
Step-by-step explanation:
You can have a maximum of 3 groups. This is due to the fact that you only have 3 sopranos to equally divide between groups. Over 3 you would have a group lacking a soprano so 3 is the greatest you can make it.
y>3x+6
y>4/3x-5 <- (The sign is greater than or equal to btw)