Question 89862
One grocery clerk can stock a shelf in 30 minutes, wheras a second clerk requires 45 minutes to do the same job. If the two clerks worked together, how many minutes would it take to stock the shelf?

First clerk's work rate: 1/30
Second clerk's work rate: 1/45
x=the amount of time they can do it together.
Together the work rate: 1/x
{{{1/30+1/45=1/x}}}  the LCD is:90x  Multiply both sides of the equal sign by that and clear your fractions.
{{{90x(1/30+1/45)=90x(1/x)}}}
{{{90x/30+90x/45=90x/x}}}
{{{3x+2x=90}}}
{{{5x=90}}}
{{{5x/5=90/5}}}
{{{x=18}}}
It would take the two 18 minutes to do it together.
Happy Calculating!!!