Answer:

Explanation:
Since Gloria cannot pay for each minute talked but for packages of 200 minutes at the rate of $25 each, we have to make calculations according to these conditions as follows:
Month 1:
Gloria talked on her cell phone for
. So, she had to buy 2 packages of
for
each package.
Hence:

Month 2:
Gloria talked on her cell phone for
. So, she had to buy again 2 packages of
for
each package.
Hence:

Month 3:
Gloria talked on her cell phone for
. So, she had to buy 3 packages of
for
each package.
Hence:

Then, if we take the total Gloria had to pay for the frist three months, we have:
