# 8. Equations Involving Fractions

In this section, we can find the solution easily by
multiplying throughout by the **lowest common
denominator.**

### Example 1

An aquarium can be filled by one hose in 7 minutes and a second thinner hose in 10 minutes.

How long will it take to fill the tank if both hoses operate together?

### Example 2

For 2 resistors with resistances
*R*_{1}and
*R*_{2} in parallel, the combined
resistance *R* is given by:

`1/R=1/R_1+1/R_2`

For a particular circuit, the combined resistance
*R* was found to be 4 ohms (Ω),
and *R*_{1}= 10
Ω. Find
*R*_{2}.

### Example 3

A car averaged 30 km/h going from home to work and 40 km/h on the return journey. If the total time for the two journeys is 50 minutes, how far is it from home to work?

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