Question 1031393

Timmy has three times as much money invested at 5% bonds as he has in stocks paying 7%. If his annual income from the stocks and bonds is $158.40, how much has he invested in bonds?
<pre>Let amount invested in bonds and stocks, be B, and S, respectively
Then: B = 3S______{{{S = B/3}}} -------eq (i)
Also, .05B + .07S = 158.4 ---- eq (ii)
{{{.05B + .07(B/3) = 158.4}}} ------- Substituting {{{B/3}}} for S in eq (ii)
{{{.05B + .07B/3 = 158.4}}}
.15B + .07B = 475.2 ----------- Multiplying by LCD, 3 
.22B = 475.2
B, or amount invested in bonds = {{{475.2/.22}}}, or {{{highlight_green(matrix(1,1, "$2,160"))}}}