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).
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Question: 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.

Answer: 4


Question: Suppose -5*j + 6*j - 5 = 0. Solve j*y - 5 = -3*u, 5*y - u = -1 - 14 for y.

Answer: -2


Question: In base 13, what is -6b1 + 3?

Answer:
-6ab