A person invested some amount at the rate of 12% simple interest and a certain amount at the rate of 10% simple interest. He received yearly interest of Rs 130. But if he had interchanged the amounts invested, he would have received Rs 4 more as interest. How much did he invest at 12% simple interest? (a) Rs 400 (b) Rs 500 (c) Rs 700 (d) Rs 800

Explanation

Let us assume the person invested Rs x at the rate of 12 % simple interest and Rs y at
the rate of 10 % simple interest. Then,



early interest =`frac{12 {x}}{100}+ `

therefore, `frac{12 {x}}{100}+frac{10 {y}}{100}=130 `

=12 {x}+10 {y}=13000

=6 {x}+5 {y}=6 {500}({i})

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