I can't see the price for shoe rentals but the expression should be
total cost in dollars (y)=(number of games (3) X the price of a game ($4)) + price of shoes. Plug in your values and you should get y=$12+shoes.
The mean is the average so 180/50 = 3.6 therefor the mean of each donation from each sponsor is £3.60
No, her answer is not reasonable because one yard is equal to 3 feet.