Devante invests $4000 in two different accounts. The first account paid 6 %, the second account paid 11 % in interest. At the end of the first year he had earned $320 in interest. How much was in each account? $
at 6 %

$
at 11 %

Let x represent the amount of $ in the 4% account and y in the 2% account.

Then x + y = $4000 (total savings).

Interest at 4% would be  x*0.04*1 = 0.04x, and

Interest at 2% would be  y*0.02*1 = 0.02y.

Then 0.04x + 0.02y = $140 interest, total.  

We must solve this system of linear equations.

Mult. 0.04x + 0.02y = $140 by 100 to remove the fractions:

4x + 2y = $14000       We already know that x + y = $4000, so y = $4000-x.

Then  4x + 2y = $14000 becomes  4x + 2($4000-X) = $56000.

Simplifying,                                     4x + $8000 - 2x = 14000.

                                                       2x                      = $6000

                                                         x     =     $3000 at 4%

                                                         y     =      $1000 at 2%

i hope it helps :)

Step-by-step explanation: