Only Tom will catch the bus to work. He will arrive at $7.42$ if he wants to get there $3$ minutes early. John will get there at $8.12$ if he wants to get there $3$ minutes early. This is because, say the exact time was $7.50$ by Tom's watch it would be $8.00$, but he thinks this is $5$ minutes slow, so he would believe the time was $8.05$. This gives him 15 minutes so if he wanted to arrive at the bus stop at $7.57$ by his watch, the actual time would be $7.57 - 15$ minutes $ = 7.42$. The same happens for John but in the opposite way therefore he arrives $15$ minutes later, at $8.12$. (Steve, Bedlington High School, Northumberland)
Well done Suzanne, Helen, Charis, Lyndsay, Nisha and Christiane from The Mount School York, and others from The Mount School and especially Christiane who did the time line. Well done also to Kang Hong from The Chinese High School, Singapore, Laura, Ipswich High School; James, Hethersettt High School, Norwich; Alan, Bedlington High School, Northumberland.