Betty wants to invest a monthly sum of money in order to accumulate R100000 in seven years. How much must be the deposit monthly if her bank offers her an interest rate of 6% per annum compounded...

Betty wants to invest a monthly sum of money in order to accumulate R100000 in seven years. How much must be the deposit monthly if her bank offers her an interest rate of 6% per annum compounded monthly? What if she was given an interest rate of 8%?