Laurie has $46,000 invested in stocks and bonds. The amount invested in stocks is $8,000 less than four times the amount

invested in bonds. How much does Laurie have invested in bonds?

I set up the equation:

let b= bonds

b + 4b-8000 = 46,000

and I got...

b=10800

however the book has the solution...

b=13500

calculated by: 4b-8000=46000

what I don't understand is this....

if bonds + stocks = 46000

why is the equation set up as

4 x bonds - 8000 = 46000

and not

bonds + 4 x bonds - 8000 = 46000?

thank you

Ken