There are 21 trees planted along the road divider with trees planted at opposite ends. The trees are planted at regular intervals of 20 m. If some lamp posts are to be placed along the opposite side of the road at regular intervals of 10 m, how many lamp posts are required on the opposite side of the road if lamp posts are placed at opposite ends of the road?
James has two dice: one 6-sided with numbers from 1 to 6, and one 8-sided with numbers from 1 to 8. He rolled these 2 dice. How many ways are there to get a sum of 6?
Jane has 143 marbles. She wants to give all her marbles to her 11 friends so that each friend will get the same number of marbles. How many marbles will she give to each friend?
Students are standing in the queue. There are 9 students between John and Sam. After the first 7 students left the queue, Sam became the 5th from the start, and John became the middle of the queue. How many students were there in the queue at first?
Justine is 13 years younger than her uncle Stewart. Stewart is 18 years older than Justine’s sister, Hana. Hana’s mother is 8 years older than Stewart, and 28 years older than her youngest child, Jared. If Jared is 12 years old, how old is Justine?
A safari company offers group tours that cost 100 dollars for two people and 20 dollars more for each additional person. If five people share the cost of the tour equally, how much does each person pay?