SOLUTION: 10. A motorist covered a journey of 690 km in 8 hours. He covered part of the journey at 90 km/h and the rest at 80 km/h.What was the distance that he covered at 80 km/h?

Question 393236: 10. A motorist covered a journey of 690 km in 8 hours. He covered part of the journey at 90 km/h and the rest at 80 km/h.What was the distance that he covered at 80 km/h?
Answer by josmiceli(19441) (Show Source): You can put this solution on YOUR website!
Let = the distance covered at 80 km/hr
Then = distance covered at 90 km/hr
Let = the time in hrs driven at 80 kmm/hr
The = time in hrs driven at 90 km/hr
I can write 2 equations:
(1)
(2)
-----------------------
From (1):

and, substituting:
(2)

The distance that he covered at 80 km/hr was 240 km
check:

hrs
(2)

OK
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