The treasurer of the student body at a college reported that the receipts from a recent contact totaled $916; Furthermore, he announced that 560 people had attended the concert. Students were charged $1.25 each for admission to the concert, and adults were charged $2.25 each. How many adults attended the concert?

Let's assume the number of adults who attended the concert is A.

Given:
Total receipts = $916
Number of students = 560
Student admission price = $1.25
Adult admission price = $2.25

Now, we can set up an equation based on the given information:
1.25 * 560 + 2.25 * A = 916

Simplifying the equation:
700 + 2.25A = 916

Subtracting 700 from both sides:
2.25A = 216

Dividing both sides by 2.25:
A = 96

Therefore, there were 96 adults who attended the concert.

To solve this problem, we can use a system of equations. Let's assume that the number of adults who attended the concert is A and the number of students is S.

From the given information, we can write two equations:

1) The total receipts from the concert were $916:
$1.25S + $2.25A = $916

2) The total number of people who attended the concert was 560:
S + A = 560

To solve this system of equations, we can use substitution or elimination method. Let's use elimination:

Multiply equation 2 by 1.25 to make the coefficients of S in both equations the same:

1.25(S + A) = 1.25(560)
1.25S + 1.25A = 700

Now, subtract equation 1 from equation 3:

1.25S + 1.25A - 1.25S - 2.25A = 700 - 916
-1A = -216

Divide both sides of the equation by -1:

A = 216

Therefore, there were 216 adults who attended the concert.

a+c = 560

2.25a + 1.25c = 916

now just solve for a

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