1st gift shop:
120/4 = 30 cents each
180/6 = 30 cents each
390/13 = 30 cents each
2nd gift shop:
204/7 = 29.14 cents each
192/8 = 24 cents each
270 /9 = 30 cents each
360/10 = 36 cents each
so if both gift shops have a fixed price then the 9 post cards would be the answer since it matches 30 each like the 1st gift store
Answer:

Step-by-step explanation:
sine of A = 
opposite = 5
adjacent = 12
hypotenuse = 13
$10.50 X 35 would give you your answer which would equal $367.5
Using an exponential function, it is found that:
a) 
b) 37.5 grams of the gas remains after 3.8 days.
c) The amount remaining will be of 10 grams after approximately 11 days.
<h3>What is an exponential function?</h3>
A decaying exponential function is modeled by:

In which:
- A(0) is the initial value.
- r is the decay rate, as a decimal.
Item a:
We start with 75 grams, and then work with a half-life of 3.8 days, hence the amount after t daus is given by:

Item b:
This is N when t = 3.8, hence:

37.5 grams of the gas remains after 3.8 days.
Item c:
This is t for which N(t) = 10, hence:







The amount remaining will be of 10 grams after approximately 11 days.
More can be learned about exponential functions at brainly.com/question/25537936