Answer:
A. You may set the variables in either order. But for argument sake, let's set as follows:
x = Amount of bookshelves
y = Amount of tables
B. Because of the amount of things you need to make, the following is an inequality using those variables.
x + y > 25
Plus you can determine a second inequality based on the amount of money that you have to spend.
20x + 45y < 675
Finally you may also add in that each value must be greater than or equal to zero, since they cannot have negative tables.
C. By solving the system and looking at basic constraints when graphed, you can see the feasible region has 4 vertices.
(0,0)
(18, 7)
(0, 15)
(33.75, 0) or (33, 0) if you insist on rounding.
Step-by-step explanation: Good luck and hope this helps :)