Write the equation y = x - 4in standard form (Ax + By = C)

y = x - 4

move y to the right side and 4 to the left side

and you will get

4 = x - y which is the same as x - y = 4

28+24=52
So we make a sum of what's going to equal 52 in small packets.
I found 4x13=52. 13 would be the number of packets
BUT!! Since it MUST be equal dark and milk and we have 28 and 26,
you would have to eliminate 1 pack because all 4 would be milk chocolate.
So that is only 12 packets.
4 per pack so that would be 2 dark and 2 milk per packet.