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 -u = 3*w - 10, -3*w = -4*w - 2*u. Suppose -w*d + 15 = 3. Solve o = -d*o + 16 for o.
4

How many meters are there in fourty-three halves of a kilometer?
21500

What is 0.7183641 millimeters in nanometers?

718364.1