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).

[EX Q]: Let u be (285/38)/(1/4). Suppose d = 5*x - 3, 0*d = -4*d - 5*x + 13. Solve 0 = 4*n - 3*f - 13 - 18, -5*n + d*f + u = 0 for n.
[EX A]: 4

[EX Q]: Let y be -6 + 56 - 1*-2. Let h(k) = k**3 + 6*k**2 - k + 7. Let l be h(-6). What is the greatest common factor of y and l?
[EX A]: 13

[EX Q]: What is prob of sequence rrr when three letters picked without replacement from bbbrbbbbbwrrwrrrrr?
[EX A]:
7/102