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]: Four letters picked without replacement from bbbsbbbsbbkkkssbbb. What is prob of picking 2 s and 2 b?
[A]: 11/102


[Q]: What is the next term in -147, -149, -151, -153?
[A]: -155


[Q]: Three letters picked without replacement from iie. Give prob of sequence eii.
[A]:
1/3