Principal = 109,000
Return - 9,920
Return = (principal x rate x time)/100
X = the amount invested at 12%
Then 102000- x = the amount invested at 8%
9920 = (x*12)/100 + (109000-x*8)100
x = 30,000
a) 30,000 is invested at 12%
79,000 is invested at 8%
b) The 12% investment is riskier so if all the money was in that account the investor could lose all his money.