5 times a number is 4 more than twice a number

5 times a number is 4 more than twice a number

The phrase a number means an arbitrary variable, let's call it x.
x

5 times a number:
5x

Twice a number means we multiply x by 2:
2x

4 more than twice a number
2x + 4

The word is means equal to, so we set 5x equal to 2x + 4
5x = 2x + 4