Answer:
informal is the first sentence and formal is the second sentence.
I would write about something that you are passionate about.

To prevent warping, thin, organic bonded wheels such as those used for cutting-off should be laid flat on a horizontal surface of steel or similar rigid material away from excessive heat and moisture.22 To minimise deterioration, wheels must be stored in a room which is dry and not subject to extreme temperatures.
Early adulthood or middle adulthood. both involve career choices but in my opinion it’s middle adulthood