You want to order posters by mail. Each poster costs $10.00,
and you have to pay $4.00 for shipping. Let x be the number
of posters you buy and y the total cost of the order.
1. What is the equation that you would use to show the total cost.?
2. How much do 4 posters cost, including shipping.?
3. How much do 15 posters cost, including shipping.?
4. If you order 20 posters at once does it cost the same including shipping, as two separate orders of 10 posters each.? Explain your answer.