Question

what is the unit rate for the ratio \\(\frac{90 \text{ calculators}}{6 \text{ classrooms}}\\)?
\\(\frac{90 \text{ calculators}}{6 \text{ classrooms}} \frac{\div 6}{\div 6} = \frac{15 \text{ calculators}}{1 \text{ classroom}}\\)
\\(\frac{90 \text{ calculators}}{6 \text{ classrooms}} \frac{\div 90}{\div 6} = \frac{1 \text{ calculator}}{1 \text{ classroom}}\\)
\\(\frac{90 \text{ calculators}}{6 \text{ classrooms}} \frac{\div 2}{\div 2} = \frac{45 \text{ calculators}}{3 \text{ classrooms}}\\)
\\(\frac{6 \text{ classrooms}}{90 \text{ calculators}} \frac{\div 6}{\div 90} = \frac{1 \text{ classroom}}{1 \text{ calculator}}\\)

Explanation:

Step1: Define unit rate goal

Unit rate = $\frac{\text{Quantity}}{\text{1 unit of denominator}}$

Step2: Normalize denominator to 1

Divide numerator/denominator by 6:
$\frac{90 \div 6}{6 \div 6} = \frac{15}{1}$ calculators per classroom

Step3: Match correct option

Only first option follows valid unit rate calculation.

Answer:

A. $\frac{90 \text{ calculators}}{6 \text{ classrooms}} \frac{\div6}{\div6} = \frac{15 \text{ calculators}}{1 \text{ classroom}}$