conversations.from: human
conversations.value: I need help with this problem:
  For the funfair, the school organizers ordered 30 rolls of tickets. Each roll of tickets has 100 tickets. The 4th graders bought 30% of the tickets while the 5th graders bought 50% of the remaining tickets. Then the 6th graders bought a total of 100 tickets. How many tickets were left unsold?
conversations.from: assistant
conversations.value: There were a total of 30 x 100 = 3000 tickets ordered by the school organizers.
  The 4th graders bought 3000 x 30/100 = 900 tickets.
  So, there were 3000 - 900 = 2100 tickets left for the other two grade levels.
  The 5th graders bought 2100 x 50/100 = 1050 tickets.
  So, 2100 - 1050 = 1050 tickets were left then.
  Since 100 tickets were bought by the 6th graders, therefore 1050 - 100 = 950 tickets were left unsold.