6.8k, and 48.2k, the math is a little more involved.
    We would start by adding all the resistances together and dividing that result into the B+ voltage, as the result would give us the maximum possible current flow with this voltage and total resistance.  Then we would multiply that current against each resistance to determine the voltage developed across it.
    To graph the three resistances starts the same way with the maximum current. Just as before, we start by adding all the resistances together and dividing that result into the B+ voltage. We then find that value at the Y axis and draw a horizontal line across the graph. The next step is to plot the first and last resistances as we would in the two resistance case. The intersection of the horizontal current line with the first line marks the voltage across the first resistance. It also defines the beginning voltage of the voltage that spans the second resistance. The intersection of the horizontal current line with the last line marks the ending voltage of the voltage across the second resistance and the beginning of the voltage across the last resistance with the B+ voltage defining the ending voltage.

Vacuum Tubes
   The advantage the vacuum tube enjoys over the transistor or MOSFET is consistency. Two 6DJ8's from different manufactures will differ by only 10% lets say. And two 6DJ8's from the same manufacture will differ by usually no more than 5%. This is a fantastic degree of consistency compared to the transistors, as a 30% difference is often sold as tightly matched. It was this constancy in both operation and characteristics that made graphing a tube's plate curves and determining operating points worthwhile endeavors.

pg. 8

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