For the first part:
Every shirt she grabs, will cost her dollars, so if she grabs 3 shirts, then the cost of the shirts is:
[tex]12+12+12=3(12)[/tex]
With the same rationale, if she grabs 2 pairs of jeans, the cost of the jeans is:
[tex]19+19=2(19)[/tex]
So, her total is:
[tex]3(12)+2(19)[/tex]
If you subtract 3 from the total, then the expression is:
[tex]3(12)+2(19)-3=36+38-3=71[/tex]
For the second part:
If she's paying 3 less for each shirt, then the cost of 3 shirts will become:
[tex](12-3)+(12-3)+(12-3)=3(12-3)[/tex]
In the same fashion, for the two jeans:
[tex](19-3)+(19-3)=2(19-3)[/tex]
So the expression for the total cost is:
[tex]3(12-3)+2(19-3)=36-9+38-6=59[/tex]
For number three:
The amounts are different because the cost of the total purchase is different than the cost of each element that makes up the total purchase.
For number four:
If you're the owner, you want to give the smallest amount of discount (the one in part 1/a).
So you could clarify by saying there's 3 dollars of the TOTAL purchase's cost.
