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: Calculate prob of sequence bnbq when four letters picked without replacement from {c: 3, u: 1, q: 1, d: 2, b: 5, n: 1}.

Answer: 1/858


Question: Four letters picked without replacement from {e: 3, q: 9, r: 1, o: 2, c: 3}. Give prob of sequence ccoq.

Answer: 1/680


Question: Two letters picked without replacement from pppppppf. What is prob of picking 1 p and 1 f?

Answer:
1/4