What is the value of y?

If i have 20$ and i gave 5$ away how much i got

Alcoa was $10.02 a share yesterday. today it is at $9.75 a share. if you own 50 shares, did ou have capital gain or loss ? how much of a gain or loss did you have ? express the capital gain/loss as a percent of the original price

Determine if the equation defines y as a function of x: 2xy = 1. yes o no