to find the common ratio in a geometric sequence, u divide the second term by the first term. 20/80 = 1/4 <== common ratio
Terms are found in a geometric sequence by multiplying each number by the common ratio to get to the next number.
start with 80
80 1/4 = 80/4 = 20
20 1/4 = 20/4 = 5
5 1/4 = 5/4
5/4 1/4 = 5/16 <===
5/16 1/4 = 5/64 <===
5/64 1/4 = 5/256 <===
