Algebra help, Income earned on an IRA investment help?

Question

I need some help on setting up this problem, and how to find the formula to get the correct answer.. this sounds like a different language like where do I start? Can I put this in a table or a chart to get the equations? 

Here it is: A student receives a yearly income of $4,900 from a $70,000  account set up by her grandparents to help fund his education. From this educational account $20,000 is invested in a secure Treasury bond earning 4.5% yearly interest. What rate of return must he earn on the rest of this investment to produce the yearly income of $4,900?

Answer 1

Given that a student receives a yearly income of $4,900 from a $70,000 account.

From  $70,000 in the account, $ 20, 000 is invested @4.5% yearly interest, thus earning [(4.5*20,000)/100]=$900

Thus money remaining in the account, ($70,000-$20,000)=$50,000 this must earn yearly ($4900-$900)= $4000, at least, 4.5% yearly interest

Therefore,he must earn on the rest of this investment of $50,000, $4000 per year.

Hence the rate of return on the rest of $50,000= [(4000/50,000)*100] per cent= 8 per cent.

 

Therefor he must earn  on the rest of this investment @ 8%