Answer. By adding the proportionality constant .
Explanation:
suppose '<em>x' a </em>is directly proportional to the<em> 'y' , </em>where<em> x </em>and <em>y </em>are variables:
<em>x </em>∝ <em>y</em>
with an input of constant value 'K' proportionality relation gets converted into an equation:
<em>x = </em>K <em>y</em>
For example : Gravitational force is directly proportional to the product of two masses and inversely proportional to the square of the distance between the two masses.
F ∝
To convert this proportionality relation constant 'G' was introduced known as gravitational constant whose value remains constant under every conditions.