Answer:

Step-by-step explanation:
You have the following functions:

Therefore
indicates that you must divide both functions, as you can see below:

Simplify it. Therefore, you obtain:

Part a: the first cereal is y=7x and the second one is y=10x so they are $3 apart.
part b: y=7*4 (28) and y=10*4 (40) is $12 apart so she will save $12 each month.
512 root 3 equals 886.810
Horizontal, by the way don listen to that just trying to get points