+128707 (1/1+r)30/r-100=0
So we have
30 / [(1 +r ) (r )] - 100 = 0
Add 100 to both sides...this gives
30 / [(1 +r ) (r )] = 100 Now multiply both sides by [(1 +r ) (r )] This gives us
30 = 100 [(1 +r ) (r )] Let's do some simplification on the right side
30 = 100r (1 + r)
30 = 100r + 100r^2
Now, let's divide everything by 10 to reduce the numbers
3 = 10r + 10r^2 And rearranging things a bit, we have
10r^2 + 10r - 3 = 0
This won't factor. so using the on-site solver, we have
{r=-(((sqrt(55)+5)/10)), r=((sqrt(55)-5)/10)}
So r has two values
The first one ≈ -1.24
And the second one ≈ .242
Not very nice and neat, but that's it 
