first of all u have to read the concept of Ratio and proportion and keep them fixed in ur mind...........
what is Ratio ? The number of times one quantity contains another quantity of the same kind is called the ratioof the two quantities..
now its type-
Consequent >In the ratio 2 :3 , 2 is the antecedent and 3 is the consequent.
Compound Ratio > Ratios are compound by multiplying together the antecedents for a new antecedent, and the consequents for a new consequent.
Inverse Ratio > If 2:3 be the given ratio, then 1/2: 1/3 or 3 :2 is called its inverse or reciprocal ratio.
Now what is Proportion ?
Consider the two ratios:
1st ratio 2nd ratio
6 : 18 8 : 24
Since 6 is one-third of 18, and 8 is one –third of 24, the two ratios are equal. The equality of ratio is called proportion.
The number 6, 18, 8 and 24 are said to be in proportion.