Answer: C= 0.25 + 0.20n
Explanation:
Let n be the number of ounces of the letters.
As per given,
Cost per ounce = $0.45
Additional cost per ounce = $0.20
So, the equation to represent the total cost, C, to mail a first class letter that weighs n ounces will be
C= 0.45 + (n-1)(0.20)
⇒ C= 0.45 + 0.20n-0.20
⇒ C= 0.25 + 0.20n
Hence, the required equation is C= 0.25 + 0.20n .