Answer: 25 tickets
Step-by-step explanation:
First, we need to make an equation representing the cost(c)
Let "a" be the number of tickets sold.
C = 500 + 10a; where c is equivalent to the price of the concert.
Next, we have to make an equation for amount they will make.
Let a = amount sold
c has to be equal to or greater than 30a
so, 500 + 10a >= 30a
Isolate the variable, -10a on each side
500 >= 20a
divide. 25 >= a
Therefore, the convention must sell 25 tickets or more to break even.