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]: Let f(c) = 53*c + 6. Let p be f(3). What is the highest common divisor of p and 15?
[A]: 15


[Q]: Let d = -25 - -162. What is the tens digit of d?
[A]: 3


[Q]: Let x = 17 - 12. Suppose 0 = -f - 2*f - l + 61, 105 = x*f + 5*l. What is the highest common divisor of 30 and f?
[A]:
10