Answer is 11
Just trust me
I'm guessing the sum is supposed to be

Split the summand into partial fractions:


If
, then

If
, then

This means

Consider the
th partial sum of the series:

The sum telescopes so that

and as
, the second term vanishes and leaves us with

Answer:
Since x is an exponent, y = 15 × 8ˣ represents an exponential function.
Answer:
Total pictures = 84+12 = 96
roll of films = 96 / 24 = 4
she used 4 rolls