Enrique takes out a student loan to pay for his college tuition thus year at an annual interest rate of 4% for 20 years. find the amount of the loan if the interest paid was $16,400.

I used the equation i=prt. (interest= principle*rate*time) But for this equation you can use p= i / rt

16400=.04*20*p
16400=0.8p

16400/0.8= 20500
20500= p 

The principle or the amount of the loan is $20,500. 

Logical equivalent of the give question is its contrapositive