Gears are supposed to be softer than worms or pinions so they don't cause as much wear. Each tooth of a worm or pinion meshes with the teeth of the gear many more times in it's life than a tooth on the larger gear, two hard teeth meshing will wear more than a hard ans soft teeth. Having a steel gear would cause the worm to wear out too fast. Ideally the worm wheel should be phosphor bronze but bronze is expensive and plastic is cheap.
The payment is called premium.
Premium payment refers to the specific amount of payment required periodically (monthly or yearly) by the insurer to provide coverage under a given insurance plans such as life insurance, auto insurance, and house insurance for a defined period of time. In Jan's case, he is required to pay monthly to cover the insurance for his car.
This would be door-in-the-face. He originally asked for a high amount of money and his mom said no, yet his mom is more willing to lend him the smaller amount of money. The son probably knew that his mom wouldn't give him $30 but when he asks for $10 after it his mom probably thought that it was more reasonable. Had the son asked for $5 and after being rejected asked his mom for $10 his mother probably said no to the $10
Hope this helped!