Please need help with this question.. I know the answer but I'm not sure about it . It say:

Complete the following problems:

i. Insert the missing numbers: 15,25,.....,45,55,..

ii. 2, 4, 6, 8, ....,12,14

iii. A ferry can take 6 cars across the river in one trip. There are 24 cars waiting to cross the river, How many trips will the ferry have to do to take all the cars across. One trip is across the river and back.

iv. If 100 pieces of small squares represent one room and 25 of those squares take up an art space, what is the fraction of room taken by art space. Using this example, identify two(2) strategies to demonstrate fractions to students.

The questions say:

In each of your responses, explain the method you used to reach your answer??

This is the question I'm stuck on, I know the answers but I'm not sure about it. Please help??