The Russian financial crisis of 1998 caused its currency to be dramatically devalued. What is the percentage

Question:

The Russian financial crisis of 1998 caused its currency to be dramatically devalued. What is the percentage change in value of a $100 million investment in Russia when the changes from $1 = 6 rubles to $1 = 21 rubles?

Exchange Rate
The value of one currency for the purpose of conversion to another. Exchange Rate means on any day, for purposes of determining the Dollar Equivalent of any currency other than Dollars, the rate at which such currency may be exchanged into Dollars...