I am going to set x=bonds and y=cds equation one x+y=32000 equation 2 x=y+8000 substitute equation 2 back into equation 1 (y+8000)+y=32000 2y+8000=32000 2y=24000 y=12000(cds) now you can take this y value and plug it back into either equation you want x=12000+8000 x=20000(bonds)