littrellk001
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While driving from​ Chicago, Brent had a visibility problem due to the fog. After 1 1/2
​hours, the fog lifted and he was able to increase his speed by 44 ​mph, driving another 2 and 1/2 hours. If the entire trip was 206 ​miles, how fast was he traveling in the​ fog?

Brents rate of speed in the fog was ____mph.



Two Snails are 391 centimeters apart. They crawl toward each other at rates that differ by 1 ​cm/min. After 23 ​minutes, they meet. How fast is each snail​ crawling?
The Slower snail is moving at ____cm/min.
The faster snail is moving at ___cm/min.


Two crews are laying blacktop on a road. They start at the same time at opposite ends of a 8​-mile road and work toward one another. One crew lays blacktop at an average rate of 0.5 mile a day faster than the other crew. If the two crews meet after 3.2 ​days, find the rate of each crew.

The rate of the faster crew is ____ miles per day.
The rate of the slower crew is ____ miles per day.

Respuesta :

kritter1
1) Let x be the original speed that he was driving; 

x mph ---> 1.5 hours 
x+44 mph --> 2.5 hours 

1.5x + 2.5(x+44)=206 
1.5x+2.5x+110=206 
4x=206-110 
4x=96 
x=24 
Therefore, he was travelling at 24 mph in the fog. 

2) Let x be the speed of 1 snail, 
The other snail travels at the speed of x+1 cm/min 

23x+23(x+1)=391 <-- solve for x 
23x+23x+23=391 
46x=368 
x=368/46 
x=8 

Therefore one of the snail travels at 8 cm/min while the other goes at 9 cm/min 

7) Let x be one crew 
Then the other crew would be working at x+0.5 

3.2x+3.2(x0.5)=8 <-- solve for x 
3.2x+1.6x=8 
4.8x=8 
x=8/4.8 
x=1.6666 or 1.7 miles 

Therefore, one of the crew does 1.7 miles per day and the other crew does (0.5*1.7)=0.85 miles

Hope I helped :)