How do i round the number to those explanations and do question 2 so confused

1) Nearest thousand: 457,000 (Look at the thousandths place. Is the number closer to 457,000 or 456,000?)
Hundred: 457,000 (Look at the hundredths place. Is the number closer to 456,000 or 457,000?)
Ten: 456,990 (Look at the tenths place. Is the number closer to 456,980 or 456,990?)

2) The value of the expression when x=6 is 27. Explanation:
6x-7
6(6)-7
36-7
27
The value of the expression when x=3 is 11
Explanation:
6x-7
6(3)-7
18-7
11