Answer:
6.5 hours
Step-by-step explanation:
The required time = x
(70 + 50) * x = 780
120 x = 780
x = 780/120 = 6.5 hours
the measure is 140, I basically summed all of the angles of a polygon of “n”, which is 7, then I did 7-2 times 180 (900) so I can finally add up all of your measurements