Last ! . visitors to a carnival can buy an unlimited-ride pass for $50 or an entrance-only pass for $20. in one day, 282 passes were sold for a total of $10,680. how many unlimited-ride passes were sold?

see you know that there were 282
passes sold right so the equation is x+y=282
where x and y are the respective types of tickets sold

now x+y=282

hence y=282-x

now see the amount collect is $10680

that is =>50x+20y=10680

try to think a lil' here now substitute that equation which i gave you in the previous comment and viola ... you get x to be 168

To answer the question, let x be the number of unlimited-ride pass for $50 and y be the number of entrance-only pass for $20. The following equations are useful to answer the question above,
                                       x + y = 282
                                 50x + 20y = 10,680
Solving for the variables above gives x = 168 and y = 114.
Therefore, there are 168 unlimited-ride passes that were sold. 

Why are u not just putting the numbers this is to much