Answer:
![\left\{\begin{matrix}x + y = 300\qquad\qquad [1]\\ 9y + 4x = 1,670\qquad\qquad [2]\end{matrix}\right.](https://img.qammunity.org/2021/formulas/mathematics/college/ch8cxsxqz9t8mt0rffw038li4ygpg35qgs.png)
Explanation:
System of Equations
Let's call:
x=Number of student tickets
y=Number of adult tickets
Conditions:
A total of 300 people bought tickets. The equation to model this condition is:
![x + y = 300\qquad\qquad [1]](https://img.qammunity.org/2021/formulas/mathematics/college/ue6mpibw1wtbvhhsn99lzb15rjjhbg6u1f.png)
Each adult ticket costs $9. If y adults paid for the concert, then 9y dollars of the total come from adults.
Each student ticket costs $4. If x students paid for the concert, then 4x dollars of the total come from students.
The total raised by The Lehman band was $1,670, thus:
![9y + 4x = 1,670\qquad\qquad [2]](https://img.qammunity.org/2021/formulas/mathematics/college/86a6si9dizsx0vxievga4z2t8x6o2dhiq8.png)
The system of equations is:
![\left\{\begin{matrix}x + y = 300\qquad\qquad [1]\\ 9y + 4x = 1,670\qquad\qquad [2]\end{matrix}\right.](https://img.qammunity.org/2021/formulas/mathematics/college/ch8cxsxqz9t8mt0rffw038li4ygpg35qgs.png)