In order to calculate the total amount after 2 years, let's use the formula:

Where P is the principal, r is the interest rate, n is a factor that is related to the compound period and t is the time in years.
Using P = 50000, r = 0.04 and n = 12 (compounded monthly, so 12 periods of compound in a year), we have:

So the total paid is $54157.15, and the interest is $4157.15.