Question 96939
Let x= cost of a child's ticket
x+2= cost of a adult's ticket
3x= cost of 3 child's tickets

3x+x+2 = $20
4x+2 = $20
4x = $20-$2
4x/4 = $18/4
x = $4.50

therefore : x+2= $4.50 + $2 = $6.50