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 5 = -3*r - 4. Let b(f) = 3*f**2 + 2*f - 3. Let c be b(r). Calculate the highest common divisor of c and 6.
6

Calculate the least common multiple of 21 and (-3 - 7/(-2))*10.
105

Let l = -20 - -38. Suppose 0 = w - 9. Calculate the highest common factor of l and w.

9

