Answer:
$4000
Step-by-step explanation:
Let B represent amount invested in account 'b'.
We have been given that an amount of $12,000 that Boris invested in fund a returned a 6% profit.
So the profit earned from fund 'a' would be [tex]12,000\times\frac{6}{100}=12,000(0.06)[/tex].
We are also told that the amount that he invested in fund b returned at 2% profit. So the profit earned from fund 'b' would be [tex]B\times\frac{2}{100}=B(0.02)=0.02B[/tex].
Further, both funds together returned a 5%. We can represent this information as:
[tex](12,000+B)\times\frac{5}{100}=0.05(12,000+B)[/tex]
Now, we will equate profit earned from account 'a' and 'b' with profit earned from both accounts as:
[tex]12,000(0.06)+0.02B=0.05(12,000+B)[/tex]
[tex]720+0.02B=600+0.05B[/tex]
[tex]600+0.05B=720+0.02B[/tex]
[tex]600-600+0.05B=720-600+0.02B[/tex]
[tex]0.05B=120+0.02B[/tex]
[tex]0.05B-0.02B=120+0.02B-0.02B[/tex]
[tex]0.03B=120[/tex]
[tex]\frac{0.03B}{0.03}=\frac{120}{0.03}[/tex]
[tex]B=4000[/tex]
Therefore, Jason invested $4000 in fund 'b'.