One times three is three. I was not awarded either a 2x base miles bonus nor a 2x normally accrued miles bonus. I was awarded a 1.5x base miles bonus. A 1.5x bonus plus 1x base = 2.5x, not 3x.

Note that DL flyers were actually awarded a 2x base miles bonus. Apparently only DL's own frequent fliers are entitled to correct math, since they actually received 0.5x more MQMs than all of us lowly NW fliers.

Of course, even the DL fliers only received 2.5x normally accrued miles, so I still find the promotion misleading even for them, but there's at least a defensible mathematical argument there (they did not include the class of service bonus in the calculation).