Purchase price of article = $5,555 Down payment = $555 Number of payments = 42 True annual interest rate=18% Monthly Payment= $

The answer to the monthly payment is $257.1428571 or $258.

How to get the answer:
Simply minus $5555 to $555. You get $5000. 
Then, divide $5000 to the number of payments which is 42. (5000/42)
For that, you get a total of 119.047619. But that is not the final answer yet.
Next, we will multiply 119.047619 to 12, because we are looking for the monthly payment and we were given an "annual" rate. Annual means yearly and every year we have twelve (12) months. In that case, 119.047619 multiplied by 12 is equal to 1428.571428. Still, it is not the final answer.
The last step is, we will multiply the answer 1428.571428 to 18% or .18 and we get a total of 257.142857. Since we used the unit $ then we will a dollar for the answer. Completing the answer to the ]question, we get a total of $257.142857 or $258 for the monthly payment.