If the teacher takes 15 minutes to mark 1 question paper. Then they will probably take 30 minutes to grade 2 question paper. Because 15 minutes+15 minutes=30 minutes. Then if you and another 15 minutes which will be 40 minutes because 15 minutes+15 minutes+15 minutes=40 minutes.
Hence, the teacher will mark 3 question papers in 40 minutes
No, because it says bridge B has twice as many so there are 40 cars for 2 hours because it says twice as much time. So the unit rate is 20 cars each hour, so there will be the same unit rate.
