How are zero identified in a rational expression??? Please help

X/y + 4y/x divided by x/y - 2y/x explain as in depth as you can how you simplfied the fractions. i don't know where to start on this : /

Sun country bus lines has 80000 shares of stock outstanding what would the dividend per share of stock be from a dividends declaration of 109600

Will mark brainliest for correct answer! i have been on this problem for an hour and can't find the answer. i'm begging here! incase you cant read the instructions in the picture because of too much or too little lighting: note: enter your answer and show all the steps that you use to solve this problem in the space provided. write a list of steps that are needed to find the measure of b. provide all steps as clear as possible, !