An investment firm recommends that a client invest in bonds rated? AAA, A, and B

An investment firm recommends that a client invest in bonds rated? AAA, A, and B. The average yield on AAA bonds is 5?%, on A bonds 7?%, and on B bonds 12?%. The client wants to invest twice as much in AAA bonds as in B bonds. How much should be invested in each type of bond under the following? conditions?
A.  The total investment is ?$9,000?, and the investor wants an annual return of ?$650 on the three investments.
B.  The values in part A are changed to ?$21,000 and ?$1,520?, respectively.