What was the % increase in the population of City K from 1980 to 1990?

1) In 1970 the population of City K was 160,000.
2) In 1980 the population of City K was 20% greater than it was in 1970, and in 1990 the population of City K was 30% greater than it was in 1970.

Statement 1) Not Sufficient

Statement 2) [(P90 - P80)/P80] * 100

[(P70+0.3P70)-(P70+0.2P70]) / 1.2P70 * 100

As i simplify the above I get i get 8.5 %

Is my approach right?