Okay for monthly, i = .00375. And the number of months, n=66.
So we have x * s angle 66 = 4800
Which becomes x * (1.00375^66 - 1)/.00375 = 4800
So, x is 64.23, which is the payment per month which will accumulate to 4800 after 66 months, assuming compounding interest and payment at the end of each month.