Let x be the amount she investment at 6%. Then the amount invested at 10% is 3x, and the investment at 8% is the rest (2600-x-3x) = (2600-4x) dollars. The total interest is the sum of partial interests 0.06x + 0.10*(3x) + 0.08*(2600-4x) = 224 dollars. Simplify; express x and calculate x == 400 dollars. Hence her investments are: $400 at 6%; $1200 at 10% and 2600-4*400 = $1000 at 8%. ANSWER CHECK. 0.06*400 + 0.1*1200 + 0.08*1000 = 224 dollars. ! Correct !