The number of tickets needed for the rollercoaster is 3 rides × 4 tickets/ride = <<3*4=12>>12 tickets.
The number of tickets needed for the Catapult is 2 rides × 4 tickets/ride = <<2*4=8>>8 tickets.
The number of tickets needed for the Ferris wheel is 1 ride × 1 ticket/ride = <<1*1=1>>1 ticket.
Turner needs 12 tickets + 8 tickets + 1 tickets = <<12+8+1=21>>21 tickets.
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