You can choose from the first letter 7 ways. For each of those 7 ways to choose the first letter, you can chose the second letter also. As well as the 3rd, 4th, 5th, 6th, and 7th. So you would multiply or use powers (7x7x7). Which would give you the answer of 343. There is 343 ways that "algebra" can be arranged.
(I'm in the 7th grade)
