Final answer:
To find the total cost of the dinner, calculate the tip as 18% of the bill and then add it to the bill amount.
Step-by-step explanation:
To find the total cost of the dinner, we need to calculate the tip and add it to the bill. The tip is 18% of the bill, so we can find it by multiplying the bill amount by 0.18. In this case, the bill amount is $72, so the tip is $72 x 0.18 = $<<72*0.18=12.96>>12.96.
To find the total cost of the dinner, we need to add the bill amount and the tip. The bill amount is $72 and the tip is $12.96, so the total cost of the dinner is $72 + $12.96 = $<<72+12.96=84.96>>84.96.