Three pieces are left. Hope this helps!
... Max sure is hungry.
a. The first variable is x and the second variable is y.
b. The equations are
and 
Step-by-step explanation:
Step 1:
The first step is to define the variables. The variables can be any two symbols, letters, characters, etc.
Here let the first variable be x and the let the second variable be y.
So the variables are defined as x and y.
Step 2:
The sum of the given variables is 12.
The first variable + the second variable = 12,

The difference between the two variables is 4.
The first variable - the second variable = 4.

Step 3:
If we add both the equations we get,
and 
x = 8 and y = 4.
Not sure if this is what your looking for but 25x10=250
Y = 12x......y = 12(4).....y = 48.....so she pays $ 48 for the old brand when buying 4 boxes
y = 8x...y = 8(4)......y = 32...so she pays $ 32 for the brand she changed to, when buying 4 boxes
so the super saving brand would save her (48 - 32) = $ 16 per month
Answer:
I believe the answer is 48 gallons.
Step-by-step explanation:
Multiply 1.6 by 30 and you get 48