Seasonal Index problem.........help me

Here's the problem:

The seasonal indices of the sales of garment of a particular type ina certain shop are given below,

----------Quarter -------------Seasonal Index

------------1----------------------97

------------2----------------------85

------------3----------------------83

------------4----------------------135

if the total in the first quarter of a year be worth Rs.20,000 and sales are expected to raise by 5% in each quarter, determine how much of garments of this type be kept in stock by the shop owner to meet the demand for each of three quarters of the year?

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Please explain how to solve and what are the fundamentals should i equip with, to solve this kinda problems with ease. Thanks. :)