Every day, you get paid $50 for working 4 hours and $15 for each additional hour you work. one day you get paid $140. how many hours did you work?

4 hours = $50

$140 - 50 =$90 

$90/15 = 6 extra hours..

4 hours + 6 hours = 10 hours.

total 10 hours 

Well, you get $50 every 4 hours, and 50 + 50 = 100
You now have the 100. You have worked at least 8 hours.
You can only get to 130 with the 15. So somewhere in there, you worked less than a whole hour. 
Now you have to divide 60 by 3 to get how you get to 40.
You will get 20 as your answer, and every 20 minutes over time, you get $5 so you can say this as an equation
100 + 30 + 10= $140