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).

[Q]: Let a(c) = -c**3 - 13*c**2 - 23*c - 5. Let s be a(-11). Calculate the highest common factor of s and 30.
[A]: 6


[Q]: Suppose -c + 4*v + 2 = -24, -4*c - 3*v + 9 = 0. Solve 2*b - c = -b for b.
[A]: 2


[Q]: Two letters picked without replacement from {o: 3, e: 1, n: 3, r: 1, a: 2, d: 3}. Give prob of sequence de.
[A]:
1/52