Multiply dollars / unit * units. It is actually a useful thing to know. Many thing are done using the tools this question requires.

Steve takes home 308.56 dollars. The answer is B.
Part a: you would get 3x+4=22
Part b: you would get 6 as your answer
Prime factorization is 2*2*2*2*2*2
2 sets of triples can be made
None
x^13
4sets of triples one left over
y^15
5sets of triples