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

Let q = 10 - -75. Suppose 2*s = 2*t + 30, 5*s - q = s - t. Suppose -4*i + 4 + 5 = -a, 4*a - i = 24. Solve -s = -2*g + a*g for g.
-4

Convert 5272.542 nanograms to grams.

0.000005272542