Does anyone know the answer to this?

Which of the following system of equation is not equal to the system of equations is not equal to the system of equations shown below

Determine the relationship of ab and cd given the following points

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