41. The vendor sells both types of apples, meaning that he can sell his 30 lbs of apples in two ways. Therefore, we add the two sizes of apple bunches, and that leaves us with 5f + 2.5t = 30, and thus the answer is B.
42. There's an easy way to solve this. In a quadratic function of the form ax² + bx + c, the 2 (real) roots must always multiply to c, and add to b. The roots of our function are -1 and 6. -1 * 6 = -6, and -1 + 6 = 5. So, we are looking for something that is x² + 5x - 6, which would be A.
43. Since you took the boxes "out" of the bookcase, you would subtract 18. This leaves us with choice A and C. Because the bookcase can hold "no more than" t books, t must less than or equal to 8b. So, we are looking for something that is equivalent to t ≤ 8b - 18, which is A.
