We want to select 3 pairs of people from a group of 6.

We use the formula:

n! / (r! * (n -r)!)

where n = 6 and r = 2

combinations = 6! / (2! * 4!) =

combinations = 6 * 5 / 2

combinations = 15

Source:

1728.com/combinat.htm

Let the price of adult's ticket be

the expression for the child's ticket is

The price of adult's ticket during off-peak season is

The price of child's ticket during off-peak season is

The total cost paid by The Sandlers is $78

The equation is

=

rearranging to solve the equation

The price of one adult's ticket is $56 (normal price) and the price of one child's ticket is $50

**Answer:**

**a = 11,390,625.**

**Step-by-step explanation:**

a^x/6 = (a^1/6)^x

(a^1/6)^x = 15^x so:

a^1/6 = 15

1/6 ln a = ln 15

ln a = 6 ln 15

ln a = 16.2483

a = 11390625.