## Using Mixed Units of Measurement in the Metric System

Performing arithmetic operations on measurements with mixed units of measures in the **metric system** requires the same care we used in the **U.S. system**. But it may be easier because of the relation of the units to the powers of \(10.\) We still must make sure to add or subtract like units.

## Example

Ryland is \(1.6\) meters tall. His younger brother is \(85\) centimeters tall. How much taller is Ryland than his younger brother?

### Solution

We will subtract the lengths in meters. Convert \(85\) centimeters to meters by moving the decimal \(2\) places to the left; \(85\) cm is the same as \(0.85\) m.

Now that both measurements are in meters, subtract to find out how much taller Ryland is than his brother.

\(\begin{array}{}\hfill \text{1.60 m}\\ \hfill \underset{\text{_______}}{\text{−0.85 m}}\\ \hfill \text{0.75 m}\end{array}\)

Ryland is \(0.75\) meters taller than his brother.

## Example

Dena’s recipe for lentil soup calls for \(150\) milliliters of olive oil. Dena wants to triple the recipe. How many liters of olive oil will she need?

### Solution

We will find the amount of olive oil in milliliters then convert to liters.

Triple 150 mL | |

Translate to algebra. | \(3·150\phantom{\rule{0.2em}{0ex}}\text{mL}\) |

Multiply. | \(450\phantom{\rule{0.2em}{0ex}}\text{mL}\) |

Convert to liters. | \(450\phantom{\rule{0.2em}{0ex}}\text{mL}·\frac{0.001\phantom{\rule{0.2em}{0ex}}\text{L}}{1\phantom{\rule{0.2em}{0ex}}\text{mL}}\) |

Simplify. | \(0.45\phantom{\rule{0.2em}{0ex}}\text{L}\) |

Dena needs 0.45 liter of olive oil. |