Level 3
The number of lemons a fruit seller bought in December was 30% more than in November. In January, he bought 50% less lemons than in December. If there were 3577 more lemons in November than January, how many lemons did the fruit seller buy in November?
Level 3
In an office tower of 600 workers, 35% of the staff is the same as 70% of the number of visitors. How many less visitors than staff are there in the office tower?
Level 3
Sam took 2 hours to walk from Building A to Building B which was 6 km away. On his way back from Building B to Building A, he increased his average walking speed by 1 km/h. How long did he take for his journey back?