4 trays are needed because your number is 3.75 and you need another tray for the rest
b must be equal to -6 for infinitely many solutions for system of equations
and 
<u>Solution:
</u>
Need to calculate value of b so that given system of equations have an infinite number of solutions

Let us bring the equations in same form for sake of simplicity in comparison

Now we have two equations

Let us first see what is requirement for system of equations have an infinite number of solutions
If
and
are two equation
then the given system of equation has no infinitely many solutions.
In our case,

As for infinitely many solutions 

Hence b must be equal to -6 for infinitely many solutions for system of equations
and
I assume you are looking for the total. The total amount in the account will be $4,781.54 if the interest is compounded annually.
If she is earning 6% interest, the balance in her account will be multiplied by 1.06 each year.
You can evaluate the following expression to find the total.
Answer:
× π10 = 7
Explanation:
The formula to find arc length is
× 
Simply plug in radius and arc length to get your equation.