Which of the following must be equal to zero for all real numbers x ?

I.-~$\frac{1}{x}$~

II. x + (-x)

III.~$x^0$~

Craig sells major appliances. For each appliance he sells, Craig receives a commission of $50 plus 10 percent of the selling price. During one particular week Craig sold 6 appliances for selling prices totaling $3,620. What was the total of Craig's commissions for that week?

A certain fishing boat is chartered by 6 people who are to contribute equally to the total charter cost of $480. If each person contributes equally to a $150 down payment, how much of the charter cost will each person still owe?

Last year if 97 percent of the revenues of a company came from domestic sources and the remaining revenues, totaling $450,000, came from foreign sources, what was the total of the company's revenues?

Last week Jack worked 70 hours and earned $1,260.If he earned his regular hourly wage for the first 40 hours worked, 1~$\frac{1}{2}$~times his regular hourly wage for the next 20 hours worked, and 2 times his regular hourly wage for the remaining 10 hours worked, what was his regular hourly wage?

If the numbers~$\frac{17}{24}$~ ,~$\frac{1}{2}$~,~$\frac{3}{8}$~,~$\frac{3}{4}$~and ~$\frac{9}{16}$~ were ordered from greatest to least, the middle number of the resulting sequence would be

What is the maximum number of 1~$\frac{1}{4}$~ foot pieces of wire that can be cut from a wire that is 24 feet long?

2x + 2y = -4

4 x + y = 1

In the system of equations above, what is the value of x ?