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.
Let the cost of the shoe be x , y , z in country A, B , C respectively in 1990. In 1995, they became 5x, 9y, 13z due to inflation(that's what the index meant). Now, the difference is 4x, 8y, 12z which is all the same 72$ . From this, x=18 ; y= 9 ; z=6 ; 5x=90; 9y = 81; 13z= 78 ; ans- 90:81:78 = 30:27:26