Question 814154
r = the ratio between terms

a = initial term of the sequence

a, ar, ar^2, ar^3 would be
a, ar, 63, ar^3, 567.


The way to go from 63 to 567 is {{{63*r*r=567}}}.
{{{r^2=567/63}}}
{{{r^2=9}}}
{{{highlight(r=3)}}}  
From this, find that {{{highlight(a=7)}}}.


You should be able to finish getting the answer to your question using your lower-level skills from the found values for a and r.