a number plus four added to the difference between three and twice the number?
Let's try to write this in math language while reading it-
(a number plus 4) N+4
(added to) + (the difference between three and twice the number) (3 - 2N)
N + 4 + (3 - 2N)
N + 4 + 3 - 2N
N + 7 - 2N
7 - N
your answer is 7 - N unless you were given more information than shown above.