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).

Let k = 5811/122 - 8/61. Let l = 2143/345 + -34/23. Let r = l + -13/45. Calculate the common denominator of k and r.
18

What is ((-104)/(-182))/((-12)/14)?
-2/3

Let f be 4 + (-10)/(-5) + 1. What is the greatest common factor of 1 and f?

1