\

Part a:

Write an expression for total cost of the lunch, 4.5$ + 4.5$ + 4.5$

= 4.5$(1 + 1 + 1)               (Distributive property: a(b + c) = ab + ac)

= 4.5$(3)                            (Add: 1 + 1 + 1 = 3)

= 13.50$                            (Multiply: )

Part b:

Amount in Billie’s hand = 20$.

Amount spent for lunch = 13.50$.

Left over amount .

Cost of a cold sandwich = 2$ \ \

Number of sandwiches Billie can be purchased

= 3.25                                                           (Divide: )

So, Billie can buy 3 cold sandwiches with the amount left over.

Amount spent for lunch is 13.50$.

Billie can buy 3 cold sandwiches with the amount left over.