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]: Let v = -7 - -11. Suppose 0 = 5*n + n - 78. Suppose v*a + n = p, -p + 15 = 5*a + 2. What is the tens digit of p?
[EX A]: 1

[EX Q]: How many months are there in 1/4 of a century?
[EX A]: 300

[EX Q]: Two letters picked without replacement from {c: 2, x: 4, h: 1, j: 1, k: 1}. Give prob of picking 1 k and 1 x.
[EX A]:
1/9