Answer: The answer is:
d=220, b=300
Step-by-step explanation:
You could solve this problem using a series of equations:
d+b=520
b-80=d
How I solve this is:
If d+b=520, you could divide 520 by 2 and say that d and b's average is 260 (though that is not their value).
Then , you know that the difference between them is 80. Since the average is 260, you could add half of 80 (which is 40) and subtract the same to get 220 and 300, which, as you can see, have a difference of 80 and add up to 520. Now you have to find out which is which.
Since 80 fewer tickets were purchased at the door than before the concert (d+80=b (the second equation)), you know that the number of tickets at the door is the lesser number, making the answer:
d=220, b=300
