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).

Example Input: Three letters picked without replacement from {f: 4, u: 6, g: 7, d: 1}. Give prob of picking 1 f and 2 g.
Example Output: 7/68

Example Input: Calculate prob of sequence pd when two letters picked without replacement from {d: 2, c: 1, m: 2, p: 2, z: 1}.
Example Output: 1/14

Example Input: What is next in -51, -93, -131, -165, -195, -221?
Example Output:
-243