Hello i wondering if anyone could give me a hand solving this

Given

1. the sum of the geometric progression := S

2. the number of terms := n

3. the first term := t

Can you get an equation for the common ratio???

finite G.P S = t * ( 1 - r^n)/(1 - r)

the number i workin off are

S = 292.618

n = 15

t = 50

i dont know the sequence as i'm using this for a c++ program and numbers vary!

Anto!!!