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).

Suppose -4*s - 3 = -47. What is the least common multiple of 21 and s?
231

Suppose -5*b = -4*l - 14, 3*b + 4 = 6*b + 2*l. Let c(a) be the second derivative of a**3/6 - 2*a**2 + a. What is the remainder when c(7) is divided by b?
1

Suppose 2*b + 2*b + 212 = 0. Let u = b + 93. Suppose -4*f + 75 = -3*s, -2*s - u = -2*f - 0*s. Calculate the greatest common divisor of 90 and f.

15