a movie theater sold a total of 148 students tickets and adult tickets. each student ticket cost 6$ and each adult tickets cost 9$. if the movie theater made 1,188$ , how many adult tickets did they sell

Let A= adult tickets and S= student tickets
A+S=148
9A+6S=1,188
You can plug into a calculator or by hand is shown below
-6(A+S)=-6(148) Checking the answer
-6A-6S=-888 A=100
+ 100+S=148
9A+6S=1,188 S=48
——————— 9(100)+6(S)=1,188
3A+0S=300 900+6S=1,188
1/3(3A)=1/3(300) 6S=288
A=100 S=48

And to check is on the right side