Question 25646
Let number of couples be "x".
So, number of couple-people is 2x.
Then, number of single-people is 180-2x.
Value of couple-people tickets is 5(x)
Value of single-people tickets is 3(180-2x)=540-6x
EQUATION:
 Value + Value = 475 dollars
 5x+540-6x=475
        -x=-65
         x=65 (number of couples)

Cheers,
Stan H.