SOLUTION: Mr. Santos traveled for 2 hours at a constant speed. Because of patholes, he reduce his speed by 7 km per hour for the next 2 hours. if he traveled 206 km, what was his speed on th

Algebra ->  Coordinate Systems and Linear Equations  -> Lessons -> SOLUTION: Mr. Santos traveled for 2 hours at a constant speed. Because of patholes, he reduce his speed by 7 km per hour for the next 2 hours. if he traveled 206 km, what was his speed on th      Log On


   



Question 118233: Mr. Santos traveled for 2 hours at a constant speed. Because of patholes, he reduce his speed by 7 km per hour for the next 2 hours. if he traveled 206 km, what was his speed on the first part of the trip?
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
There are are 2 parts of the trip. I'll call them a and b
For parta,
speed = s%5Ba%5D+=+skm/hr
time = 2hours
distance = d%5Ba%5D+=+dkm
For partb.
speed = s%5Bb%5D+=+s-7
time = 2hours
distance = d%5Bb%5D+=+206+-+d km
d%5Ba%5D%2Fs%5Ba%5D+=+d%5Bb%5D+%2F+s%5Bb%5D
d+%2F+s+=+%28206+-+d%29+%2F+%28s+-+7%29
Also, I know that d+%2F+s+=+2
d+=+2s
d+%2F+s+=+%28206+-+d%29+%2F+%28s+-+7%29
2s+%2F+s+=+%28206+-+2s%29+%2F+%28s+-+7%29
2%28s+-+7%29+=+206+-+2s
2s+-+14+=+206+-+2s
4s+=+220
s+=+55 km/hr answer
check answer
d+=+2s
d+=+110km
d+%2F+s+=+%28206+-+d%29+%2F+%28s+-+7%29
110+%2F+55+=+%28206+-+110%29+%2F+48
2+=+96+%2F+48
2+=+2
OK