instruction:
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).
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:
Suppose 0*r = 5*r - 35. What is the units digit of r?
answer:
7


question:
Suppose -i = -2*i + 22. What is the tens digit of i?
answer:

2