Answer:
We add up all elements of ratio then place smaller value and set as a fraction if both fractions are equal from 2 sets of ratios then we have equivalent ratios.
Example set of ratios we see 1:2 and 6:3 is equivalent
as 6:3 could be 6/9 just like 3/9 is and 3/9 is ratio equivalent shown can be shown 3/9 = 1/3
As 1:2 = 1/3 or 2/3 and its 1/3 thats shown in workings.