Answer:
B) The equation that can be used to find the cost of the given  coat
   is C + 0.08 C  = 86.40
Step-by-step explanation:
The selling price of the coat = $ 86.40
The percentage of sales tax= 8 %
Let us assume the cost price of the coat = Â C
Now, the tax is calculated on the cost price.
So, 8 % Â of C Â = [tex]\frac{8}{100} Â \times C = 0.08 C[/tex]
⇒ The tax on the cost price C = 0.08 C
Selling Price  = COST PRICE + Tax Amount
or, $86. 40 = Â C + 0.08 C
⇒ C + 0.08 C  = 86.40
Hence, the equation that can be used to find the cost of the given  coat
is C + 0.08 C Â = 86.40