Using the simple interests, we can say that:
Amanda borrowed $4500 from her parents.Amanda borrowed $500 from the credit union.In the question, we are given that Amanda borrowed $5000 from two sources: her parents and a credit union. Her parents charged 5% simple interest and the credit union charged 6% simple interest.We are asked to calculate how much did she borrow from her parents, and how much did she borrow from the credit union, if after 1 year, she paid $255 in interest.We assume that Amanda borrows $x from her parents.Then we know that she would have borrowed $(5000 - x) from the credit union as the total borrowed amount was $5000.We know that the simple interest (S.I.) on $P, at the rate of r%, for a period of t years, is calculated as S.I. = Prt/100.Thus, for the amount she borrowed from her parents, the simple interest is, S.I. = (x)(5)(1)/100 = x/20.For the amount she borrowed from the credit union, the simple interest is,S.I. = (5000 - x)(6)(1)/100 = (30000 - 6x)/100 = 300 - 3x/50.Thus, the total interest Amanda needs to pay is x/20 + 300 - 3x/50 = 300 - x/100.But, we are given that the total interest Amanda pays is $255.Thus, we can write that 255 = 300 - x/100,or, x/100 = 300 - 255,or, x/100 = 45,or, x = 4500.Thus, the amount Amanda borrows from her parents = $4500.The amount she borrows from the credit union is $(5000 - 4500) = $500.Thus, Using simple interests, we can say that:Amanda borrowed $4500 from her parents.Amanda borrowed $500 from the credit union.