A child´s ticket costs $4 and adults ticket costs $8. If we want one of each we need to add both numbers together, 4 plus 8 equals 12. The total cost of a child ticket and an adult ticket is $12.
The questions asked to write an equation; the equation would be:
C+A=T it could also be written as A+C=T, T=A+C or T=C+A.
