Here is what'd you do:
Ignore the $78.80 at the moment and focus on the $6.60 an hour and she worked 8 hours.
So, basically you'd do 6.60 * 8 (or 660*8 if you aren't allowed a calculator)
For 660*8 you'd get:
5280. move the decimal over twice.
$52.80 , if you are allowed a calculator you would have just done 6.60 * 8
So now you know she got $52.80 just working hourly.
Subtract $78.80 from $52.80
Your Answer:
Stephanie made $26 from tips.