Answer:
16 singles, 56 couples
Explanation:
There's two linear equations that we can make: one for money and one for people. Let the number of single tickets be s and the number of couple tickets be c .
We know that the amount of money we make is $ = 20 s + 35 c = 2280
We also how many people can come P = 1 s + 2 c = 128
We know that both s are the same and both c are the same. We have two unknowns and two equations, so we can do some algebra to solve for each.
Take the first minus twenty times the second: 20 s + 35 c =2280
− 20 s − 40 c = − 2560
− 5 c = − 280 ⇒ c = 56
Plugging this back into the second equation, s + 2 c = s + 2 ⋅ 56 = s + 112 = 128 ⇒ s = 16