Answer: 57
<u>Step-by-step explanation:</u>
First, create a system of equations using the cost as one equation and the quantity as the other.
Let c represent a child ticket and a represent an adult ticket, then
Cost Equation: 6.50c + 9.90a = 999.80
Quantity Equation: c + a = 124
I am going to use substitution method to solve by solving the Quantity Equation for c --> c = 124 - a
and substituting that c-value into the Cost Equation -->
6.50(124 - a) + 9.90a = 999.80
806 - 6.50a + 9.90a = 999.80
806 + 3.4a = 999.80
3.4a = 193.80
a = 57
