Tricky math question!!please help:)?

The annual interest on Sid Carrington's three investments amounted to $33250: 5% on a savings account, 7% on mutual funds, and 15% on bonds. If the amount of Sid's investment in bonds was triple the amount of his investment in the savings account, and the interest earned from his investment in bonds was equal to the dividends he received from his investment in mutual funds, find how much money he placed in each type of investment.

Assuming "interest" on mutual funds is equal to dividends in the problem;

Givens:

$33250 = .05s + .07m + .15b
b=3(s)
.15b=.07m

simultaneous equasions:

$33250 = .05s + .07m + .15b
0= 3s - b
0= .07m - .15b
$33250 = 3.05s+ .14m - b

Progressive substitution to find savings investment s

$33250 = 3.05s + .3b - b
$33250 = 3.05s - .7b
$33250 = 3.05s - .7(3)s
$33250 = 3.05s - 2.10s
$33250 = .95s
$33250/.95= s
$35000 = s

Progressive substitution to find bond investment b
b= $35000(3)
b= $105,000= bond investment


Progressive substitution to find mutual funds investment m

.15($105,000) =.07m
.15($105,000)/.07= m
$225,000 = mutual fund investment

do it yourself - you need the practice for your exam!

x = savings
y = mutual funds
z = bonds

We know:
1) .05x + .07y + .15z = $33250 and...
2) 3z = x and...
3) .07y = .15z


Basically, you start substituting variables from #2 and #3 into the equation #1

Edit: Did you get it?

Edit(2): Not sure if you got it... the answers are(to help you check if your answer is correct):
Bond Amount = $73,888.89
Savings Amount = $221,666.67
Mutual Fund Amount = $158,333.34

Plug these back into the formula to confirm.