Aretired woman has $70,000 to invest but needs to make $9,000 a year from the interest to meet certain living expenses. one bond investment pays 15% annual interest. the rest of it she wants to put in a cd that pays 7%. set up and solve the equation for how much the woman should invest in each option to sustain exactly a $9,000 annual return.

Let, x be the amount she invest in the bond which pays 15% of interest.

Then, $70000-x would be the amount she would be investing in a CD that pays 7% of interest.

We know the simple interest formula is:

Case I: Let be the interest she gets on investing $x amount in bond which gives 15% of interest.

Thus,

Hence we have now,

Case II: Let be the interest she gets on investing $(70000-x) amount in CD which gives 7% of interest.

Thus,

Hence we have now,

Since, the woman needs to make a total interest of $9000 each year,

⇒The amount she invest in bond = x= $51,250

Thus, the amount she invest in CD = $70,000 - x= $70,000 - $51,250= $18,750

Therefore, the amount that women should invest in bond is $51,250 and in CD   is $18,750 so that she can get a total interest of $9000 every year.