The given values
.
The sum of a geometric series is
.
Where
is first term and r is common ratio.
(Substitute
)
(Subtract denominator:
)
Apply multiplication property of equality: a = b then
.
(Multiply each side by
)
(Cancel common terms)
(Multiply:
)
Apply quotient power property:
.

(Evaluate powers:
)
(Subtract:
)
Apply multiplication property of equality: a = b then
.
(Multiply each side by negative 128)
(Cancel common terms)
Apply division property of equality: a = b then
.
(Divide each side by 127)
(Cancel common terms)
(Divide:
)
The value of
.