Combined Work Rates of Tom and Jerry

Tom and Jerry are working on a project together. Tom can complete the project alone in 6 hours, while Jerry can finish it alone in 4 hours. If they work together, how long will it take them to complete the project?

Let $T$ represent the total time (in hours) it will take for both of them to complete the project together. The rate at which Tom works is $\f\frac{1}{6}$ of the project per hour and the rate at which Jerry works is $\f\frac{1}{4}$ of the project per hour. The combined rate of both of them working together can be expressed as:

$\f\frac{1}{T} = \f\frac{1}{6} + \f\frac{1}{4}$.