Question 364308
Here is what we know 220 boarded the airplane in Los Angeles and they would all have to pay at least $80.

220 X 80 = 17,600

We also know the total of all fares was $23,800.

So lets subtract the minimum amount we know everyone paid ($17,600) from the total amount collected ($23,800)

23,800 - 17,600 = 6,200

Now we know that the remaining people on the plane paid $6,200 to continue to Albuquerque. The cost for the flight from LA to ALB is $120 and the cost from LA to Phoenix is $80. We already said everone paid the $80 so lets subtract the two totals.

120 - 80 = 40

This now means that who ever stayed on to fly to ALB paid an extra $40 and the total of all of those people is $6200. So divide the total by the cost.

6200 divided by 40 = 155

This means 155 people paid the $120. Now just subtract 155 from 220 (total number starting the trip). 65 people got off the airplaine in Phoenix.

Lets check our answer: 65 x $80 = $5,200; 155 x $120 = $18,600; 
$5,200 + $18,600 = $23,800.