To write down notes while you are in the class because I find it easier to explain it to yourself. You can use flashcards or study your textbook. I find the first suggestion best.
1 - 8
2 - 16
3 - 32
x - +200
Each lemonade has a profit of $1, so the number of cups of lemonade he sells is the same as the amount of dollars he has. You just need to add each previous day's total to the next day's, doubling the amount of cups from the previous day's for each new day.
4 - (32 x 2 = ) 64
8 + 16 + 32 + 64 = 120. We need at least $80 dollars more, so we continue.
5 - (64 x 2 = ) 128
120 + 128 = $248.00 That's more than enough, so Tom will have enough money for his bike after the fifth day of selling lemonade.
