Adam wants to earn a total of $ 300each week by walkings dogs for $d$ hours
and mowing lawns for $m$ hours. The graph below shows all possible numbers of hours
Adam could wask dogs and mow lawns to earn exactly $ 300 a week.

Last week Adam walked dogs for the same number of hours that he mowed lawns.
He earned $ 300.
How many TOTAL hours did Adam walk dogs and mow lawns last week?
A. 30
B. 28
C. 20
D. 24