Grayson has 100 questions on a test. He answers some of the questions for 2 hours, taking two minutes for each answer, then realizes he doesn't know the rest of the questions. How many questions does Grayson leave unanswered when he submits his test?
##Solution## Each hour contains 60 minutes, so after 2 hours he took 2*60 = <<2*60=120>>120 minutes.
If each question takes two minutes, then he answered 120/2 = <<120/2=60>>60 questions.
Unanswered questions is 100-60 = <<100-60=40>>40 questions
#### 40