<human>:  Dolly wants to ride the Ferris wheel twice, the roller coaster three times, and the log ride seven times. The Ferris wheel costs 2 tickets, the roller coaster costs 5 tickets and the log ride costs 1 ticket. Dolly has 20 tickets. How many more tickets should Dolly buy?
<bot>: How many tickets does it cost to ride the Ferris wheel twice? ** It costs 2 rides x 2 tickets/ride = <<2*2=4>>4 tickets to ride the Ferris wheel twice.
How many tickets does it cost to ride the roller coaster three times? ** It costs 3 rides x 5 tickets/ride = <<3*5=15>>15 tickets to ride the roller coaster three times.
How many tickets does it cost to ride the roller coaster seven times? ** It costs 7 rides x 1 ticket/ride = <<7*1=7>>7 tickets to ride the roller coaster seven times.
How many tickets does Dolly need? ** In total Dolly needs 4 tickets + 15 tickets + 7 tickets = <<4+15+7=26>>26 tickets.
How many more tickets should Dolly buy? ** Dolly needs to buy 26 tickets - 20 tickets = <<26-20=6>>6 more tickets.
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