Problema Solution
Stan and Hilda can mow the lawn in 40 minutes if they work together. If Hilda works twice as fast as Stan, how long does it take Stan to mow the lawn alone?
Answer provided by our tutors
Let
x = the time (in hours) Hilda needs to mow the lawn alone
y = the time (in hours) Stan needs to mow the lawn alone
Together they finish the job in 40 min = 2/3 hours. For 1 hour time working together we have
1/x + 1/y = 1/(2/3)
2*x = y
The solution of the system of equations is
x = 1
y = 2
Stan needs 2 hours to mow the lawn alone.