Mr Duck invested 36000 in two accounts one yielding 7 intere

Mr. Duck invested 36,000 in two accounts, one yielding 7% interest and the other yielding 12%. If he received a total $3,520 in interest at the end of the year, how did he invest in each account of 7% _____ and 12% _____.

Solution

You need to set up two equations such that:

[{(x + y = 36000),(7%x + 12%y = 3520):}]

x,y represent the investments

[{(x + y = 36000),(7x + 12y = 352000):}]

You may use substitution method to solve the simultaneous equations, such that:

[{(x = 36000 - y),(7(36000 - y) + 12y = 352000):}]

[{(x = 36000 - y),(252000 - 7y + 12y = 352000):}]

[{(x = 36000 - y),(5y = 352000 - 252000):}]

[{(x = 36000 - y),(5y = 100000):} => {(x = 36000 - y),(y = 20000):}]

[{(x = 36000 - 20000),(y = 20000):} => {(x = 16000),(y = 20000):}]

Hence, evaluating the investments in each account yields that Mr. Duck has invested [$16000] in [7%] account and [$20000] in [12%] account.