help

[opal nacelle]

Use that the sum of the first eight terms is 81/97. So use the equation

For the sum of a geometric progression for n

Set n to 8 and equal to your 81/97

Rearrange to find r

[undone galleon]

use sum of the first 'n' terms in a gp... which is a(1-r^n) divided by 1-r

a is the first term of gp