What would be the cost for 5 of the gift cards?
$80
$90
$100
$110
Answer : $100
The graph is attached below
From the graph we can see that,
When the number of gift cards = 1 then cost = $20
When the number of gift cards = 2 then cost = $40
When the number of gift cards = 3 then cost = $60
When the number of gift cards = 4 then cost = $80
The cost is increasing by 20 dollars for each card
Hence, cost = $100 for 5 of the gift cards.