Question 1189192
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You should know and understand how to set up and solve the problem using formal algebra, something like what the other tutor showed in her response.<br>
But you can get some good mental exercise solving the problem mentally, with logical reasoning and simple arithmetic.  It might go something like this:<br>
The additional cost for a trip to Chaska is $4, so the extra cost for the 7 trips to Chaska is $28.
Subtract that from the total cost of $103 to find the remaining cost for the 7+8=15 trips is $75.
That means the cost of each of those trips is $75/15=$5.
So each trip to Waconia costs $5, and each trip to Chaska costs $5+$4 = $9.<br>
ANSWER: A round trip ticket to Waconia costs $5.<br>
Note that the calculations in this informal solution are EXACTLY the same as those used in the formal algebraic solution.<br>