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 u(n) = 5 + 3*n**3 - 4*n**3 + n + n - 3*n**2 + 7*n**2. Suppose 0 = -4*i - 2*t + 20, 3*i - 18 + 0 = -3*t. What is the units digit of u(i)?
[EX A]: 3

[EX Q]: Four letters picked without replacement from {e: 3, q: 9, r: 1, o: 2, c: 3}. Give prob of sequence ccoq.
[EX A]: 1/680

[EX Q]: Suppose 0 = -v - 1. Let r be (0 - 2)/(v/(-5)). Let c(u) = -2*u + 1. Let q be c(r). Calculate the greatest common factor of 14 and q.
[EX A]:
7