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).

[Q]: What is prob of picking 4 y when four letters picked without replacement from yyyyyyyymmmymm?
[A]: 18/143


[Q]: What is prob of sequence tt when two letters picked without replacement from {t: 2, h: 1, u: 1, m: 2}?
[A]: 1/15


[Q]: Calculate -0.5*0.26.
[A]:
-0.13