A decrease in price of good x has occurred. in the market for good y, this will lead to

This will lead to an increase in price and an increase in quantity if Good X and Y are complementary goods.

Complementary goods refers to the goods that commonly used together (such as stove and gas). When the price for one part of complementary goods fall, the sellers usually will match it up by increasing the price of the other in order to maintain the profitability