Help with multipliers? (exponential stock-value growth)

[mallorymal]

Different way:

Let P be initial value, R be return rate.

450 = P*(1+R)^2

1250=P*(1+R)^7

Using second equation divide by the first equation to cancel P:

1250/450 = (1+R)^7/(1+R)^2

25/9=(1+R)^5

Take 5th root on both sides:

1+R =(25/9)^(1/5) = 1.2267

Using first equation :

P = 450/(1+R)^2

=450/1.2267^2

=299

The answer is $299

I understand this.