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: Convert 6.264243mg to tonnes.
Example Output: 0.000000006264243

Example Input: Suppose -g - 4*g = -3*u + 29, 0 = 4*u + 3*g. Suppose -30 = -4*b - s + u*s, -s - 33 = -4*b. What is the units digit of b?
Example Output: 9

Example Input: What is prob of picking 1 x and 3 d when four letters picked without replacement from dddddddddddddxddddd?
Example Output:
4/19