Juan paid $7000 for a new car. 20% was his downpayment he financed the rest with a 36 month fixed loan with an APR of 5%. what's his finance...

The down payment made is 20% 0f $7000.

Therefore, the rest of the loan amount = 7000-(20/100)7000 =$5600.

If  P is the amount of loan to be paid in 36 monthly equal instalments, with a rate of APR 5% or 0.05 per dollar, then the monthly interest rate per dollar = 0.05/12= r say. Then ,

P(1+r)^n = A[(1+r)^n -1]/r, where A is the fixed instalment of the loan.

Therefore, A = [P(1+r)^36]*r/((1+r)^n - 1)...........(1)

In this problem, P = $5600, r = 0.05/12. Substituting these values in (1) to get the A.

So, A = $5600(1.05)^36)(0.05/12)/ ((1.05)^36 -1)

= $167.84 in each instalment.

So Juan goes on paying 167.84 for 36 months, which sums to 167*36 =  $6042.24

So, Juan pays in total $1400+$167.84*36 = $7442.24 for the loan of $7000. So the total financial charge  he paid is whatever he paid over and above $7000 = $(7442.24-7000) = $420.24.