Louise K. answered 11/17/14
Tutor
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Former Teacher, Experienced Tutor, many subjects, especially math
Here we only have enough info for one equation, so we can't have two variables, but we have two prices. So we can't have A = advance tickets and T = tickets sold on the night of the show. What to do?
Think of it this way. If we let A = the number of advance sale tickets, then 150 - A = the number of tickets sold on the night of the reception. We can get rid of the second variable (T) by representing it in terms of the first, using the fact we know about the total number of tickets. So, here are our variable definitions:
A = advance tickets
150 - A = night-of-show tickets
You know the price of each type of ticket, and the total revenue. So, you multiply the price times each number of tickets and add the results together to get the total, as follows:
140A + 160(150 - A) = 21,800 -->Use distribution next!
140A + 24000 - 160A = 21,800
-20A = -2200 -->Don't worry about the negatives, they'll go away when you divide through by -20
A = 110 <-- This is your advance number
150-110 = 40 <-- This is your night-of-show number