When solving a system of two equations via substitution, there will always be only one answer.
a. true
b. false?

No false.
Remember the solution(s) to a system of equations is where the graphs all intersect if at all.
For the case of say a system of 2 lines, you can see the different possible outcomes..
  -- If the two lines intersect at some point (x,y), that is one unique solution
  -- If the two lines are parallel to each other, you see there are no intersection points and therefore this system of two parallel lines has no solutuion.
  -- If the two lines overlap, really the same line written as a multiple of the other line, then you see they intersect at all points along the line, here there are infinite solutions.

Jerry does cases per hour (Rounded to 2 decimal places). As we cannot do 0.11 cases. We can say Jerry does 2 cases per hour.

Step-by-step explanation:

to find the number of cases per hour, we have to divide the number of cases by number of hours taken for those cases,

Number of cases per hour =

                                             = cases per hour

                                             = cases per hour

                                             = cases per hour

                                              = cases per hour (Rounded to 2 decimal places)

As we cannot do 0.11 cases. We can say Jerry does 2 cases per hour.