Hello please help prize is brainliest

Which values for a and b will create infinitely many solutions for this system of equations? ax-y=8 2x+y=b

Barney & noblet customers can choose to purchase a membership for $25 per year members receive 10% off all store purchases 1. how much would a member pay per year if he bought $50 worth of items each year? 2. write a slope-intercept equation that expresses how much a member pays per year using x to represent his purchases per year 3. how much would a member have to spend per year to pay off his membership fee?

An ant travels at a constant rate of 30cm every 2 minutes. at what speed does the ant travel per minute