SOLUTION: Any help would be appreciated.... At 10:00am a plane was 1600 ft above ground, at 10:40 it was 1200 ft above ground. Write an equation. Thanks

Algebra ->  Expressions-with-variables -> SOLUTION: Any help would be appreciated.... At 10:00am a plane was 1600 ft above ground, at 10:40 it was 1200 ft above ground. Write an equation. Thanks      Log On


   

Question 259032: Any help would be appreciated....
At 10:00am a plane was 1600 ft above ground, at 10:40 it was 1200 ft above ground. Write an equation.
Thanks
Answer by drk(1908) About Me  (Show Source):
You can put this solution on YOUR website!
We really have 2 coordinates in disguise here:
(0,1600) and (40,1200)
step 1 - we can find the slope as
m+=+%28y2-y1%29%2F%28x2-x1%29
putting in our x,y information, we get
m+=+%281600-1200%29%2F%280-40%29
which means
m+=+-10
--
step 2 - find the value of b using
y=mx+ b.
picking a point and using our slope, we get
1600+=+%28-10%290+%2B+b
b+=+1600
--
step 3 - write the answer as
y+=+-10x+%2B+1600