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).
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Question: Suppose -16 = 4*q - 0*q. Let z be (-50)/q + (-1)/(-2). Suppose -2*a + 37 = -67. Calculate the greatest common factor of z and a.

Answer: 13


Question: What is 15/4 of a millisecond in microseconds?

Answer: 3750


Question: What comes next: -269, -539, -809, -1079, -1349, -1619?

Answer:
-1889