Let x be the number of single tickets sold.
Let y be the number of couple tickets sold.
So
The total number of people attended is x + 2y.
The total money earned from selling the tickets is 20x + 35y.
As 128 people attended, setting x + 2y equal to 128, we have:
x + 2y = 128 ....................(1)
As the total revenue from selling tickets is $2,280, setting 20x + 35y equal to 2280, we have:
20x + 35y = 2280 ................(2)
Next solve the simultaneous equations (1) and (2).
From equation (1), we get x = 128 - 2y.
Substituting it into equation (2), we have:
20(128 - 2y) + 35y = 2280
Solving for y, we obtain:
2560 - 40y + 35y = 2280
-40y + 35y = 2280 - 2560
-5y = -280
y = (-280)/(-5)
y = 56
Substituting y = 56 into x = 128 - 2y, we have
x = 128 - 2*56 = 16
So 16 single and 56 couple tickets were sold.
It is most likely equal to two soccer fields
Since she has seven key the probability that the first one will open the door is
if it takes three attempts to open the door,the probability is
if the three attempts would not work
then the probability that the fourth attempt will open the door is
hope this helps