How can I solve this question?

Question

On average , a girl reaches 90% of her final height when she is 11 years old ,and 98% of her final height when she is 17 years old . Anna is 11 year old , she is 150 cm tall.Estimate her height when she is 20.Raji is 17 years old and she is 176 cm tall. Estimate her height when she is 30

Answer 1

If full height is h, at 11 years old height is .9h

.9h = 150

h = 150/.9 = 166.67 cm estimated for Anna

 

Raji:

.98h = 176

h = 176/.98 = 179.59 cm estimated for Raji