Washing machine loan

Uncle Wendell paid 350 euros for a new washing machine, which he had to borrow 40 percent. He paid off the loan for one year - 15 euros per month. How much did he pay in interest? What was the interest rate on loan?

Final Answer:

i =  40 eur
p =  28.5714 %

Step-by-step explanation:

$$\begin{gathered} A=0.40\cdot 350=140\text{eur} \\ B=15\cdot 12=180\text{eur} \\ i=B-A=180-140=40\text{eur} \end{gathered}$$

$p=100\cdot \frac{i}{A}=100\cdot \frac{40}{140}=\frac{100\cdot 40}{140}=\frac{4000}{140}=\frac{200}{7}\%=28.5714\%$

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