Which pair of ratios form a proportion? My daughter is stuck on this question and we're not sure what the answer is. I'm rusty with math skills, so I don't understand how to help her, or what approaches she's tried. Please help us!
10.5/12 and 2/5
13/7 and 7/13
9/30 and 1.5/5
7/5 and 10/8

Two numbers $a,b$ are proportional when there is an integer $A \neq 0$ and such that $a\cdot A = b$ or $ a = A \cdot b$.
You can check that the only pair of numbers that you have listed satysfying the above requirement are $\frac{9}{30}$ and $\frac{1.5}{5}$ because $\frac{9}{30} = 1 \cdot \frac{1.5}{5}$.
