I'm trying to find the sum of this geometric series but I can't find a common ratio. How do I find it?

Question

1+1/5+1/25+...

Answer 1

take the 2nd and divide by the 1st:
(1/5) ÷ 1 = 1/5

should be the same as the 3rd divided by the 2nd:
(1/25) ÷ (1/5)
= (1/25)(5/1) = 1/5

looks like r = 1/5

sum(all terms) = a/(1-r) = 1/(1-1/5)
= 1/(4/5)
= 5/4