Math word problem

Question

define variables, write an equation, and then use the equation in the solving process.

 

 

Martha can rake the leaves in her yard in 6 hours. Her younger brother can do the job in 7 hours. How long will it take them to do the job if they work together?

Answer 1

time together + time together = 1

   time alone         time alone

Let t = time together

t/6 + t/7 = 1       Multiply both sides by 42.

7t + 6t = 42

13t = 42

t = 3.23 hours  or 3 3/13