At a sushi restaurant, *nigiri* costs \4.50perserveand∗sashimi∗costs9.00 per serve. Hiroko spent a total of \45buyingxservesof∗nigiri∗andy$ serves of *sashimi*.
a. Explain why 4.5x+9y=45.
b. If Hiroko bought 4 serves of *nigiri*, how much *sashimi* did she buy?
c. If Hiroko bought 1 serve of *sashimi*, how much *nigiri* did she buy?
d. Draw the graph of 4.5x+9y=45. Mark two points on your graph to indicate your answers to b and c.