The inflation index of a country $A$ in $1995$ relative to $1990$ was $5$. Meaning that the ratio of dollars spent during $1990$ for goods compared to dollars spent for same goods is $1:5$. In country $B$ the inflation index is $9$ for the same period. In country $C$ the inflation index is $1$3. A pair of shoe cost $ \$72$ more in $1995$ than in $1990$ in all three countries. What was the ration between the price of pair of shoe in country $A,B,C$ in $1995$.
I cant get the concept of inflation index.