Question

1) A number decreased by sixteen

2) Twice a number subtracted by eight.
3) The difference of a number and twenty
4) The product of a number and seven, added to six.

Answer 1

1, x-16

2. 2x-8

3. x-20

4. 7x + 6

Explanation:

when given the phrase 'a number' they mean they want you to replace that phrase with a variable. 'a number' decreased by 16 is simply x-16.