Answer:

Step-by-step explanation:
First open the brackets

Then collect the like terms

Solve the like terms

The simplified form is

So.. 2.86 - 2.79 is the amount in decrease or 0.07
so.. if we take 2.86 as the 100%, how much is 0.07 of that in percentage?
well

solve for "x"
You only need one if you follow a pattern of
top left dot
top middle dot
middle middle dot
middle left dot
bottom left dot
bottom middle dot
bottom right dot
middle right dot
top right dot
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.