MATH-MAGIC Solve the following problems :

We have,
John and Susan placed their order at 7 : 40 am. They got it at 8 : 30 am
Therefore, time taken for wait = 8 : 30 am - 7 : 40 am
That is 50 minutes.
Hence, they were waiting 50 minutes for their food.

We have,
The chess game started at 10 : 30 am that is at 10 : 30 in morning and game ended at 12 : 30 pm that means 12 : 30 in afternoon.
To find the time taken the game last we subtract the starting time from the ending time.
Therefore, 12 : 30 - 10 : 30 = 2 hours
Hence, the game last till 2 hours.

We have,
Priya started her homework at 7 : 30 pm. She finished it at 8 : 05 pm.
To find the time taken to do it by her. We subtract starting time from the finishing time.
That is 8 : 05 pm - 7 : 30 pm = 35 minutes
Hence, Priya take 35 minutes to do her homework.