Answer:
The D cells are worth $2.20, and the C cells are worth $1.90.
Step-by-step explanation:
This can be written as:
4x + 2y = 12.60
6x + 4y =20.80
Our goal is to find one variable, then use that information to find the other.
If we multiply the top function by -1.5, we get:
-6x - 3y = -18.90
We can add this to the previous equation.
-6x - 3y = -18.90
+ 6x + 4y = 20.80
--------------------------
y = 1.90
The C cells are worth $1.90.
Plug this value into one of the other equations and solve for x.
4x + 2y = 12.60
4x + 2(1.90) = 12.60
4x + 3.80 = 12.60
4x = 8.80
x = 2.20
The D cells are worth $2.20.
Check these values in the other equation.
6x + 4y = 20.80
6(2.20) + 4(1.90) = 20.80
13.20 + 7.60 = 20.80
20.80 = 20.80
