Answer:
3 ft by 4/3 feet.
Explanation:
We have been given that a card is 9 inches by 4 inches. A printing shop will enlarge it so that the longer side is any lengths up to 3 ft. We are asked to find the dimensions of biggest enlargement.
We will use proportions to solve our given problem.
![\frac{\text{Card width}}{\text{Card length}}=\frac{\text{Enlarged width}}{\text{Enlarged length}}](https://img.qammunity.org/2021/formulas/mathematics/high-school/kisdlvd1k2htcrc0mt30jwz107cxbnyoxk.png)
Upon substituting our given values, we will get:
![\frac{\text{4 inches}}{9 \text{ inches}}=\frac{\text{Enlarged width}}{\text{3 ft}}](https://img.qammunity.org/2021/formulas/mathematics/high-school/jyqt4npobhrnk51vhj5x7a8gvcv5ebn5e3.png)
![(4)/(9)=\frac{\text{Enlarged width}}{\text{3 ft}}](https://img.qammunity.org/2021/formulas/mathematics/high-school/ym7mzimgezk31sls0c98b5udqonpxixsoh.png)
![(4)/(9)* \text{3 ft}=\frac{\text{Enlarged width}}{\text{3 ft}}* \text{3 ft}](https://img.qammunity.org/2021/formulas/mathematics/high-school/atli6j83el1zkcxbvup1cx7cidvvidw2ow.png)
![(4)/(3)* \text{ft}=\text{Enlarged width}](https://img.qammunity.org/2021/formulas/mathematics/high-school/2ww9c47mdpguske5w0tir3w5n1c8dj9ke6.png)
Therefore, the dimensions of the biggest enlargement would be 3 ft by 4/3 feet.