are there any tricks to proportions?

Question

Like is there easy ways to do it and if so how

Answer 1

yes, there are several.  consider a/b = c/d. 

 

1) TAKE RECIPROCALS OF EACH RATIO:  b/a = d/c.

 

2) CROSS-MULTIPLICATION: ad = bc.

 

3) DENOMINATOR-ADDITION PROPERTY: (a+b)/b = (c+d)/d

 

4)  INTERCHANGE OF THE EXTREMES (a and d, i.e. left numerator & right denominator): d/b = c/a

 

5) INTERCHANGE OF THE MEANS (the 'means' are b & c, i.e. left denominator & right numerator): a/c = b/d