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]: What is prob of picking 3 o and 1 z when four letters picked without replacement from zozzzozo?
[EX A]: 1/14

[EX Q]: Let z = 27 - 9. Suppose 2*t = -3*t - 4*l + 38, 4*l = 5*t - 22. What is the highest common divisor of z and t?
[EX A]: 6

[EX Q]: Three letters picked without replacement from {t: 7, z: 4, f: 8, b: 1}. Give prob of sequence tfb.
[EX A]:
7/855