Applications of Rational Functions

Question

Question:

 

It takes an older employee 15 hours to shovel the snow from a sidewalk, but a younger employee can shovel the same sidewalk in 4 hours. How long will it take them to clear the walk if they work together?

Answer 1

x/15 + x/4 = 1

 

Multiply all the terms by the LCD.  The LCD is 60.  Therefore the equation becomes 4x + 15x = 60.  NOw solve for x.  

 

19x = 60 then x = 60/19 or 3.2 hours