Question 992627
 Craig and Pam, working together, can mow the lawn in 9 hours. Working alone, Pam takes three times as long as Craig. How long does it take Craig to mow the lawn alone?

let x=hours  it takes Craig to mow the lawn alone
1/x=his work rate
3x=hours  it takes Pam to mow the lawn alone
1/3x=her work rate
sum of indv. work rates=work rate working together
1/x+1/3x=1/9
lcd:9x
9+3=x
x=12
hours  it takes Craig to mow the lawn alone=12