SOLUTION: When road repairs begin, the current speed limit will be cut by 40 km/h. It will then take at least 3.6 h to cover the same distance that can be covered in 2 h now. What is the s

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Question 696964: When road repairs begin, the current speed limit will be cut by 40 km/h. It will then take at least 3.6 h to cover the same distance that can be covered in 2 h now. What is the speed limit now?
so far i have:
x=current speed limit
x-40(greater than or equal to)3.6
Found 2 solutions by lwsshak3, josmiceli:
Answer by lwsshak3(11628) About Me  (Show Source):
You can put this solution on YOUR website!
When road repairs begin, the current speed limit will be cut by 40 km/h. It will then take at least 3.6 h to cover the same distance that can be covered in 2 h now. What is the speed limit now?
**
let=current speed limit
x-40=new speed limit
distance=travel time*speed
2x=3.6(x-40)
2x=3.6x-144
1.6x=144
x=90
current speed limit=90 km/hr

Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
You have 2 equations, 1 for before road repairs
and another after road repairs start
Let +d+ = distance in km covered before and after road repairs start
Let +s+ = the current speed limit in km/hr
--------------------------------
Driving at the speed limit before and after the repairs:
Before:
(1) +d+=+s%2A2+
After:
(2) +d+=+%28+s+-+40+%29%2A3.6+
----------------------
substitute (1) into (2)
+2s+=+%28+s+-+40+%29%2A3.6+
+2s+=+3.6s+-+144+
+1.6s+=+144+
+s+=+90+
The speed limit now is 90 km/hr
check the answer:
(1) +d+=+s%2A2+
(1) +d+=+90%2A2+
(1) +d+=+180+
and
(2) +d+=+%28+s+-+40+%29%2A3.6+
(2) +d+=+%28+90+-+40+%29%2A3.6+
(2) +d+=+50%2A3.6+
(2) +d+=+180+
OK