Given a simple high-school level math question, you are required to solve it and provide the final answer. The final answer is always a single number. These questions can range from a variety of topics like simple arithmetic, solving equations, converting a quantity from one unit to another, finding remainders/GCD/LCM, finding probabilities etc. Each question has only one correct answer. This answer can be a positive or negative integer, a fraction or a decimal number. If the answer is a negative number use the hyphen (e.g. -42) symbol for the minus sign. For decimal numbers, do not add extra zeros after the decimal point. For fractional numbers, separate the numerator and denominator using a forward slash (e.g. 3/25).

Suppose 2*y + 12 = 6*y. Suppose y = f - 15. Solve -8 = -4*w, -3*d - 4*w + f = -8*d for d.
-2

Let b(l) = l**3 - 2*l**2 - 3*l. Let g be b(3). Solve g*f + 15 = -3*f for f.
-5

Two letters picked without replacement from {f: 2, z: 4, y: 8, b: 1}. What is prob of sequence yf?

8/105