6? 7 ? 6? 3 ? 6? 8 ? 6? 4 what is horizontal is tolerance, and what is not horizontal is true tolerance.
Answer? 6? 7 B means that all elements of a belong to B.
Answer? 6? 3 B stands for a 6? 7 B but a ≠ B.
If you use it frequently, go/download the "Mathematical Tools" software, which is designed for inputting mathematical symbols, formulas and inserting function images. It's faster this way.