#1**+2 **

Let the original cost per person = C

So......the revenue collected is just 20C

When 10 more join, the cost per person is (C - 1.50)

And the revenue is 30 (C - 1.50)

And the revenue (cost for renting the bus) is the same in both cases....so

20C = (30) (C - 1.50) simplify

20C = 30C - 45 subtract 30C from both sides

-10C = - 45

C = 45/10 = 4.50

So.....the cost of renting the bus = 20 C = 20 * 4.50 = $90

CPhill Jun 22, 2019