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]: Three letters picked without replacement from {q: 5, b: 3, o: 1}. What is prob of picking 1 o and 2 b?
[EX A]: 1/28

[EX Q]: Two letters picked without replacement from {n: 2, p: 1, s: 1, c: 2, d: 1, u: 1}. Give prob of sequence sc.
[EX A]: 1/28

[EX Q]: Two letters picked without replacement from tizkx. What is prob of sequence xk?
[EX A]:
1/20