The Drama Club needs $1000 to cover the cost of the production. If the tickets are sold for a flat rate of $4 each, how many tickets must be sold to cover the expenses?

This is a simple division problem:

1000 / 4 = 250 tickets
However, this could have also been solved algebraically:

$4 = 1 ticket

$1000 = x tickets

(Above, I have basically said that of 1 ticket costs $4; then x tickets would cost $1000. The variable x shows how many tickets have to be sold to cover $1000)

4x = 1000 (cross mulitply: X * 4 and 1000 * 1)

4x/4 = 1000/4 (divide by 4 on both sides)

x = 250