human
Bertha plays tennis. Every ten games, one of her tennis balls wears out. Every five games, she loses a ball. Every four games, she buys a canister of three balls. She started with two balls and gave one to her partner. After twenty games, how many tennis balls does she have?
assistant
How many tennis balls does Bertha wear out in 20 games? ** Bertha wears out 20 / 10 = <<20/10=2>>2 tennis balls in 20 games.
How many tennis balls does Bertha lose in 20 games? ** She loses 20 / 5 = <<20/5=4>>4 tennis balls in 20 games.
How many tennis balls does Bertha buy in 20 games? ** She buys canisters of 3 * 20 / 4 = <<3*20/4=15>>15 tennis balls in 20 games.
How many tennis balls does Bertha have after twenty games? ** Bertha started with 2 balls and gave 1 away, so she has 2 + 15 - 2 - 4 - 1 = <<2+15-2-4-1=10>>10 tennis balls after twenty games.
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