Question 516807
Let x = the amount Peggy invested at 8% per annum, then the remainder ($1000-x) was invested at 9% per annum. The total interest earned on these two amounts is given as $84.00
We can express the interest earned on the two amounts as:
0.08x as the interest earned on amount x at 8% and 0.09(1000-x) as the amount earned on the remainder at 9%.  The sum of these two amounts is given as $84.00 so this can be expressed in the equation:
0.08x+0.09(1000-x) = 84 Simplify and solve for x.
0.08x+90-0.09x = 84
-0.01x+90 = 84 Subtract 90 from both sides.
-0.01x = -6 Divide by -0.01
x = 600 and 1000-x = 400
Peggy invested $600 at 8% per annum and $400 at 9% per annum.