Question

which proportion could you use to convert 90 millimeters to centimeters?
$\frac{10\text{ millimeters}}{1\text{ centimeter}}=\frac{90\text{ millimeters}}{?\text{ centimeters}}$
$\frac{10\text{ millimeters}}{1\text{ centimeter}}=\frac{?\text{ centimeters}}{90\text{ millimeters}}$
convert.
90 millimeters = centimeters

Explanation:

Step1: Set up correct proportion

We know that 1 centimeter = 10 millimeters. The correct proportion to convert 90 millimeters to centimeters is $\frac{10\text{ millimeters}}{1\text{ centimeter}}=\frac{90\text{ millimeters}}{x\text{ centimeters}}$, where $x$ is the number of centimeters we want to find.

Step2: Cross - multiply

$10\times x=90\times1$.

Step3: Solve for $x$

$x = \frac{90\times1}{10}=9$.

Answer:

9