To find out how many miles the plane would travel in 6 hours at the same speed, we first need to determine the speed of the plane.
The plane traveled 780 miles in 5 hours, so we can calculate the speed by dividing the distance by the time:
\[ \text{Speed} = \frac{\text{Distance}}{\text{Time}} = \frac{780 \text{ miles}}{5 \text{ hours}} = 156 \text{ miles per hour} \]
Now that we know the speed of the plane is 156 miles per hour, we can find out how far it would travel in 6 hours by multiplying the speed by the time:
\[ \text{Distance} = \text{Speed} \times \text{Time} = 156 \text{ miles per hour} \times 6 \text{ hours} = 936 \text{ miles} \]
Therefore, the plane would travel 936 miles in 6 hours at the same speed.