how price of related goods influence the demand? see the answer below

Related good can be of two types-

1.      COMPLIMENT GOODS- These are those goods which are used together. E.g. Car and petrol.

2.     SUBSTITUTE GOODS- These are goods which are used in place of other goods. E.g. Tea coffee.

In case of compliment goods,

Price of good 1 is inversely proportional to Demand of good 2.

So if there is an increase in the price of petrol then quantity demanded for Car will automatically decrease applying Law of Demand.

Whereas In case of substitute goods,

Price of good 1 is directly proportional to Demand of good 2.

If there is an increase in the price of tea, quantity demanded for coffee will also increase.