Hi, I was not sure how I can judge the ratio below is the same as 3/4.

It’s from Linear and Quadratic Equations Practice.

A rectangular rug covers half of a rectangular floor that is 9 feet wide and 12 feet long. If the dimensions of the rug are in the same ratio as those of the floor, how many feet long is the rug?

(A) 6

(B) 21/2

(C) 2√7

(D) 6√2

(E) 4√6

In the class, there were back solving methods.

For (B), the ratio is 10.5: 5.14, and how can I know the exact ratio?

For (D), the ratio is 8.4:5.14, and it’s the answer. but how can I know it’s 3:4?

when I divided 5.14/8.4, the result is 0.7642… and 3/4 is 0.33333…