Answer:
$26.14
Step-by-step explanation:
You want to tip the waiter 20% of your bill. First, we need to find 20% of $21.78 and then add it to the bill.
20% = 20/100 = 0.2
Now we multiply 0.2 with 21.78 to find tip amount. Shown below:
0.2 * 21.78 = $4.36
We now have to add it to original price:
$21.78 + $4.36 = $26.14
The cost of lunch bill (with tip) is $26.14