Let's call the monthly payment amount x. Since Jamal makes 12 equal monthly payments, the total amount he pays in one year is 12x. Adding the $66 registration fee, we can set up the equation:
12x + 66 = 624
Now, we can solve for x by isolating the variable:
12x = 624 - 66
12x = 558
x = 558 / 12
x ≈ 46.50
So, the monthly payment amount is approximately $46.50.