
Donald H. answered 02/12/15
Tutor
New to Wyzant
It Ain't Rocket Science
That was a correct answer. Another way to solve it, which I think has less abstraction, so may appeal to younger students, is to use variables that relate to the problem better, and simplify the steps.
First, let the number of adults be A, and the number of children be C.
We know two things:
The total number in attendance is A + C = 125
The total price, $9 times A plus $4 times C, is 9A + 4C = 775
So C = 125 - A
Substitute this value in the money equation:
9A + 4(125 -A) = 775
Hooray! Now we have an equation with only one unknown.
9A - 4A = 775 - 500
A = 55
Plugging this back in the first equation,
55 + C = 125, or
C = 70
The student should now plug these two values into the second equation to check his work!
I think this method also shows that the solution makes common sense, and demystifies algebra.