UPSC CDS 2 2018 Math Paper

X bought 4 bottles of lemon juice and Y bought one bottle of orange juice. Orange juice per bottle costs twice the cost of lemon juice per bottle. Z bought nothing but contributed ₹ 50 for his share of the drink which they mixed together and shared thecost equally. If Z’s ₹ 50 is covered from his share, then what is the cost of one bottle of orange juice ?