Solve Write a Mixed Numeral for the Answer $2 \frac{4}{5}$ Hours on the First Day And

Solve. Write a mixed numeral for the answer.
-Brian was training to run a marathon. During the three-day period before the race he decided that he would train for a total of 12 hours. If he trained for $2 \frac{4}{5}$ hours on the first day and $1 \frac{3}{10}$ hours on the second day, how many hours would he need to train on the third day?

A) $8 \mathrm{hr}$
B) $8 \frac{3}{10} \mathrm{hr}$
C) $8 \frac{9}{10} \mathrm{hr}$
D) $7 \frac{9}{10} \mathrm{hr}$