I'm not going to do the entire question, but I'll do the first part.
For the first part, you have to set up an inequality. Use context clues, such as
no more than (the one used in this sentence) to figure out what the symbol should be for the inequality.
In this case, because it is NO MORE THAN 6400, it would be:
6400

250r + 475p
where r represents the # refrigerators, and p represents the # pianos
Now that you have the equation, make the graph, then for the 3rd part, plug in 12 and 8 to r and p to see if it keeps the inequality true.
Hope this helps! :)
The answer would be b and c
1. Negative
Explanation: A negative minus a positive will be a negative
2. Negative
Explanation: If you use your order of operations a negative multiplied by a negative will be positive but since BxB would be greater than A it would be negative for example 2-8 would equal -6
B: 914-20(27.80)=X, multiply: 20(27.80)=556, 914-556=$358 :A.
C: 914-27.80=$886.20 :)