It is very easy, you'll see. Let's suppose that x is the value or result, so x=62.4(d)-210, from where you must replace d = 13 (is given in the exercise). So if you want to know how many Indian rupees you receive, operate the equation:
x = 62.4*(13) - 210
x = 811.2 - 210
x = 601.2.
In consequence, the quantity you receive is 601.2 Indian rupees.
