Since we are asked for tge graph that represent the total cost for the x numbers of lesson, it will be helpful to illustrate it first this way
for each lesson it will cost $30 dollars
1 lesson $30
2 lessons $60
3 lessons $90
4 lessons $120
5 lessons $150
So from this set of numbers , it is apparent that the grqph in letter c represents the total costs for x numbers of lessonsseethati