14. He bought seven oranges for .25. so: 7 * .25 = 1.75
he bought bananas for .15. so: b * .15 = .15b
so .15b + 1.75
15. Well we can easily see which ones only have 2 terms. a coefficient is the number connected in front of the variable. So if I said 6x then 6 is the coefficient.
in c, there are 2.terms and 6 precedes variable
16. just plug in x and y -7(3) + (-12/3) -21 - 4 -25
