<PRE><B>Question 295940</B>
    Ting can mow a lawn in 4 hours. Her boss, Renald, can mow the lawn in 3 hours. How long will il take them to mow the lawn if they work together?
.
Ting rate: 1 lawn per 4 hours
Renald rate: 1 lawn per 3 hours
.
then
Let t = hours it takes for both
t(1/4 + 1/3) = 1
multiplying both sides 12:
t(3 + 4) = 12
t(7) = 12
t = 12/7
t = 1.71 hours</PRE>