Question 950599
it took terry 7h to drive 390km from cold bay to morgan's cove. he averaged 60km/h for the first part of the trip,but was forced to complete the trip at 50km/h due to a thunderstorm. how many hours did he spend driving at 50km/h
s=distance at 60 km/hr
s/60 km/hr+390km-s/50 km/hr=7 hr Multiply each side by 300.
5s+6(390km-s)=2100hr
5s+2340-6s=2100 subtract 2340 from each side.
-s=-240 Multiply each side by -1.
s=240 km  He drove 240 km at 60 km/hr.
390km-240km=150km He drove 150 km at 50 km/hr.
150 km/50km/hr= 3hr ANSWER He spent 3 hours driving at 50 km/hr.
CHECK
240km/60km/hr+150km/50km/hr=7hr
4hr+3hr=7hr
7hr=7hr