Question

a used truck for $4,500 he made an agreement with the dealer to put $1,500 and make payments of 350 for the next 10 months that extra costs paid by taking this bill bill is equivalent to what actual yearly rate of interest

Answer 1

Ist amount paid = $1500
Making $350 for 10 months = 10*350 = $3500
Total amount paid  = 1500 + 3500 = 5000
So an amount of $5000 was paid to cover the cost of $4500 within the ten month period.
I = PRT
Interest, I = 5000 - 4500 = 500Time, t = 10 months = 10/12 = (5/6) year.Principal P = 4500
R = I /(PT)  R = 500 / (4500*5/6)
R = (500*6) / (4500*5)
R = 0.1333..
R ≈ 13.33 %  per annum.