Ratios are proportional if they represent the same relationship. One way to see if two ratios are proportional is to write them as fractions and then reduce them. If the reduced fractions are the same, your ratios are proportional.
I'm not sure what side is missing but you could use the proportions
A/B=X/Y or B/C=Y/Z or CA/=ZX. it also works if you reverse this for example B/A=Y/X
<span>The equation is e = 300 - 10t. t is greater or equal than 0 and given that e cannot be negative, 300 - 10 t greaetr or equal than 0 => 10 t greater or equal than 300, and t greater or equal than 300/10 = 30. This is the viable points are times from 0 to 10 and elevation from 300 to 0. Some points are (0,300) which is the initial point (when Rory is on the top); (1, 290); (2, 280); (3, 270); (4, 260); (5, 250); (6, 240); (10, 200), (20, 100), (30, 0).</span>
About 5 books have been signed out, so they still have 4.
For every four miles Ariana drove, Jonathan drove seven miles