Question 1143121
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With basic algebra....<br>
10a+10c = 200
13a+2c = 172<br>
Solve by any method you like.  Note that the first equation is equivalent to a+c = 20; whatever solution method you use, that will make things easier.<br>
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The same thing, doing mostly the same calculations as with algebra, but informally, using logical reasoning instead.<br>
(1) 10 adults plus 10 children equals $200, so 2 adults plus 2 children equals $200/5 = $40.
(2) Compare that to 13 adults plus 2 children equals $172; the difference is 11 adults for $132.
So each adult ticket costs $132/11 = $12; then each child ticket costs $8.