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]: Calculate the least common multiple of 21 and (-3 - 7/(-2))*10.
[EX A]: 105

[EX Q]: What is the value of (21 - 17)*(-2)/40?
[EX A]:
-1/5