how do I solve this word problem?
Carl has $10,000 to invest. You recommend that she invest in Treasury Bills that yield 6%, Treasury Bonds that yield 7%, and corporate bods that yield 8%. Carl wants to have an annual income of $680, and the amount invested in corp bonds must be half that invested in Treasurey bills. Find the amount in each investement/

Question

how do I solve this word problem?
Carl has $10,000 to invest. You recommend that she invest in Treasury Bills that yield 6%, Treasury Bonds that yield 7%, and corporate bods that yield 8%. Carl wants to have an annual income of $680, and the amount invested in corp bonds must be half that invested in Treasurey bills. Find the amount in each investement/

anonymous · Answer

let x be the amount invested in Treasury Bills, 
let y be the amount invested in Treasury Bonds,
let z be theamount invested in Corp bonds

0.06*x+0.07*y+0.08*z=680
x+y+z=10000
2z=x

you should get x=4000,y=4000,z=2000