Instructions
Enter the cabin to the left of the snow plow.
Pick up the gas can in the corner of the cabin. Carry it outside.
Carry the gas can over to the snow plow. Jump onto the platform attached to the back of the snow plow.
Drop the gas can onto the platform if it's not pulled out of your character's hands automatically. It disappears into the snow plow, which starts up.
Switch your character to Velma. Active the control panel on the rear of the snow plow.
Memorize the sequence of lights. Reproduce it when prompted to set the snow plow in motion.