Given
The average daily balance is $15
The daily periodic rate = 0.06%
The number of days in the cycle is 30
Find out the monthly finance charge.
To proof
Let us assume that the monthly finance charge = x
As given in the question
The average daily balance = $15
daily periodic rate = 0.06%,
First convert 0.06% in decimal form

= 0.0006
Daily finance charge = 0.0006 × 15
= 0.009
number of days in the cycle is 30
now
monthly finance charge
Than the equation becomes
x = 15 × 0.0006 × 30
x = 0.009× 30
x = $0.27
Thus the monthly finance charge is $0.27
Hence proved