Answer:
20-3(7)-4(3)
20-21-12
-13
20 - (3(7) - 4(3)) = ?
20 - (21 - 12) = ?
20 - 9 = 11
9 Hours
Step-by-step explanation:
720/80=9
N=1
Hope you could understand.
If you have any query, feel free to ask.