Determine whether each system of equations has no solution, one solution, or infinitely many solutions Show work please:)

The holiday party will cost $160 if 8 people attend. if there are 40 people who attend the party, how much will the holiday party cost

I'm at a bookstore with $\$35$ in my pocket and a $20\%$-off coupon. what is the cost of the most expensive book i can buy with my money and the coupon? (assume that there are books of every possible price in the bookstore. it's a large bookstore! )

Find the rate of change for the situation. you run 7 miles in one hour and 21 miles in three hours.