Rekhadidi deposited `10000Rs` of her savings in two separate banks at the same time. The rate of simple interest per annum is of `6%` in one bank and that of `7%` in other bank, after `2` years, if she gets `1280Rs` in total as interest, then find the money she had deposited separately in each of two banks.

Explanation

Let Rekhadidi deposited `Rs x` in the first bank.
`:.` She had deposited `Rs(10000-x)` in the second bank. Now, at the rate of `6%` per annum, the simple interest of `Rs x` in `2` years `=Rs (x xx6xx2)/(100)=Rs(12x)/(100)`
Again, at the rate of `7%` per annum, the simple interest of `Rs(10000-x)`
in `2` years `=Rs((10000-x)xx7xx2)/(100)=Rs(140000-14x)/(100)`
As per question, `(12x)/(100)+(140000-14x)/(100)=1280`
or, `(12x+140000-14x)/(100)=1280`
or, `140000-2x=128000`
or, `2x=140000-128000`
or, `2x=12000` or, `x=(12000)/(2)=6000`
`:.` She deposited `Rs6000` in the first bank.
`:.` In the second bank she had deposited `Rs(10000-6000)=Rs4000`
`:.` Rekhadidi had deposited `Rs6000` and `Rs4000` respectively in the two banks.