Ratio, Proportion and Unitary Method.  The comparison of two numbers or quantities by division is known as the ratio. Symbol ‘:’ is used to denote ratio. For a ratio, the two quantities must be in the same unit. If they are not, they should be expressed in the same unit before the ratio is taken. Two ratios are equivalent, if the fractions corresponding to themare equivalent. Four quantities are said to be in proportion, if the ratio of the first and the second quantities is equal to the ratio of the third and the fourth quantities. The symbol ‘::’ or ‘=’ is used to equate the two ratios. The order of terms in a proportion is…