Arithmetic sequences
The Richard family wants to build a human pyramid when they go to the beach this summer. They will put one person on top and add 2 more people for each descending row.

A.How many people will be in the seventh row?

B.Find the total number of people in a pyramid with seven rows

C. Next summer, Sarah Richard wants to build a pyramid with only the great-grandchildren. If they build it the same way. how many children are needed to make with 10 rows?