.
Let c = # of children.
The "money" equation is
c*200 + (50-c)*350 = 15250.
200c + 50*350 - 350c = 15250,
-150c = 15350 - 30*350 = 4850 ====> c = = 15.
Answer. 15 children and 50-15 = 35 adults.
Check. 15*200 + 35*350 = 15250 dollars. ! Correct !
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To see other similar solved problems on tickets, look into the lessons
- Using systems of equations to solve problems on tickets
- Three methods for solving standard (typical) problems on tickets
in this site.
Also, you have this free of charge online textbook in ALGEBRA-I in this site
- ALGEBRA-I - YOUR ONLINE TEXTBOOK.
The referred lessons are the part of this online textbook under the topic "Systems of two linear equations in two unknowns".
Save the link to this online textbook together with its description
Free of charge online textbook in ALGEBRA-I
https://www.algebra.com/algebra/homework/quadratic/lessons/ALGEBRA-I-YOUR-ONLINE-TEXTBOOK.lesson
to your archive and use it when it is needed.
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Be aware ! The solution and the answer ("5 children") by @josgarithmetic both are W R O N G.