cost = $187.60
20% down
4 months of $39.40
1.- Calculate the 20%
187,6 ------------------- 100
x -------------------- 20
x = (20 x 187.6) / 100
x = 3752/100
x = 37.52
2.- Calculate the final price
Price paid = 37.52 + 4(39.40)
Price paid = 37.52 + 157.6
= $195.12
2.- Finance charge
= 195.12 - 37.52
= $157.6