For the relationship between the number of dance lessons and the cost of them to be proportional, they have to have a direct relationship, this means, that if each time one of the variables cincreases one unit, the other is modified the k times.
Symbolically:
y=kx
Where
y represents the cost of the dance lessons
x represents the number of lessons
k represents the constant of proportionality between both variables.
Using the given information you can calculate the costant of proportionalitiy as:
k=y/x
The variation of y is not constant, i.e. the value of k changes each time x increases one unit.
This is not a proportional relationship.
