Answer:
$1.20
Explanation:
He has to leave 100% of the cost which is $5.50 + 2.50 or $8.00.
He wants to leave 115% of the $8 he has to leave.
So you set it up like
x/8 = 115/100
Then you solve for x
8(115) = 920
920/100 =9.2
So he will leave $9.20.
It then asks for just how much the tip is that he will leave so
9.2 - 8 = 1.2
So the tip is $1.20.