if you know the spot rates on the dollar/euro and the ruble/dollar then you can easily calculate the ruble/euro cross rate. the spot rate on the dollar/euro is )1.55/1 and the spot rate on the ruble/dollar is Rbl37.02/$1

now using the ruble/euro cross rate convert ruble to euro or euro to ruble.

you have Rbl 50,000 in your pocket. How much euro do you get if you convert your ruble into euro using the cross rate you calculated?