.
Let P be the number of premium tickets.
Then the number of reserved tickets is (2P+1).
Then the number of general admission seats is (85 - P - (2P+1)) = (84-3P).
The "money" equation is
39*P + 29*(2P+1) + 19*(84-3P) = 2105
39*P + 58*P - 57*P + 29 + 19*84 = 2105
40*P = 2105 - 29 - 19*84 = 480 ====> P =
= 12 premium tickets.
====> # of reserved tickets = 2P+1 = 25. # of the general admission seats = 84 - 3*12 = 48.
Answer. 12 premium, 25 reserved and 48 general admission.
Check. 12 + 25 + 48 = 85; 12*39 + 25*29 + 48*19 = 2105 dollars. ! Correct !
Solved.
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The lesson to learn from this solution:
This problem is for ONE unknown.
It is not for using the systems of equations.
Your major task is to select the basic unknown by reasonable/rational way,
then to express other unknowns via that basic variable and to built/to construct the equation to solve.
Learn from those in this forum who knows the subject and ignore those who does not know.
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To see other similar problems solved in this way, look into the lessons
- More solved word problems on a single linear equation
in this site.