In fraction form the answer would be -2 4/5.
This is an exponential growth problem. Exponential growth can be expressed mathematically in the following way:

.
Parameter a presents initial amount.
Parameter r is percentage increase.
Parameter t is time.
An equation that would describe given problem is:

t is the time in years.
I attached the graph of this function.
Answer:
x = -3, y = 1
Step-by-step explanation:
To find the value of x and y, find the determinant of original matrix, which would be 21.
Then, substitute the value of x with the solutions to the equations and find the determinant of that matrix, which is -63.
Cramer's rule says that Dx ÷ D is the value of x. So, -63 ÷ 21 = -3.
So, the x-value is -3.
You can find the determinant of the y-value in the same way, and you'll find out that y = 1.
Hope this helped! :)
3 liters of soda
1.5 pints of sherbet
4.5 cups of ice