Marisa can buy 3 oranges for 1.35 dollars ,four oranges for $1.80 or five oranges for $2.25 per second by 10 oranges for a price that fits this pattern or a bag of 10 oranges for four dollars and 25 cents which way cost less for 10 oranges explain

3 oranges= $1.35, so one orange cost $0.45
4 oranges= $1.80, one orange cost $0.45
5 oranges= $2.25, one orange cost $0.45
If one orange cost $0.45, then ten cost $4.50 ($0.45*10)

If you were to buy ten oranges are $4.25, this would make each orange $0.425 ($0.43 rounded).

This means that if you were to buy ten oranges, it would be cheaper to buy ten for $4.25, instead of buying two lots of 5 for $2.25 each.

Hope this helps :) 

The 8th term is 512