Answer: 
Step-by-step 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:

Answer:
The least number of stamps required is 
Step-by-step explanation:
Let the number of
cent stamps be
and
cent stamps be 
We have

The minimum number is obtained when more
cent stamps are used
Here
cannot be greater than
since 
Substitute 

Not possible since
is not a fraction
Substitute 

Not possible since
is not a fraction
Substitute 

Possible
Hence minimum number of stamps is

Answer:
3) C.
4) B.
5) C.
Step-by-step explanation:
Answer:
Straight 180
Reflex 210
Right 90
Acute 75
Obtuse 135
Step-by-step explanation: