Verified answer

Each series of four resisters makes 400 ohms

parallel resistances are figured by taking the reciprocal of the sums of the reciprocals so

the left two sets of 400 ohm resisters in parallel make 200 ohms

likewise the right two sets of 400 resisters also make a 200 ohm setup

adding the two 200 ohm setups together give the desired 100 ohm total resistance

so four parallel sets of four 100 ohm resistances in series give you 100 ohms

now for power capacity

each resistor in a series of 4 will handle the same current

at a fixed voltage, the current through a single 100 ohm resistor will also appear across the four parallel sets of resistors equaling 100 ohms

so each of the four parallel branches will carry 1/4 of the current.

as power is current squared times resistance

and the resistance of each individual resistor is constant at 100 ohms

by reducing the current to 1/4, we have reduced the power to 1/16

Our 4 X 4 matrix of 1 watt resistors is capable of handling 16 watts of power. Well above our desired consumption of 10 watts.

through putting the three 6K ohm resistors in parallel you're making a resistor equivalent of 2K ohm. putting that right into a sequence configuration with the 3K ohm resistor will bring about the final value you have asked for. Reminder that resistors in sequence upload, in parallel the reciprocals upload (a million/Rt = a million/R1 + a million/R2).