35-33+31-29+27-25+23-21+…+11-9+7-5+3-1?

To solve the sequence \(35 - 33 + 31 - 29 + 27 - 25 + 23 - 21 + \ldots + 11 - 9 + 7 - 5 + 3 - 1\), we can reorganize the terms for easier addition.

Let's group the positive and negative pairs:

\[ (35 - 33) + (31 - 29) + (27 - 25) + (23 - 21) + (19 - 17) + (15 - 13) + (11 - 9) + (7 - 5) + (3 - 1) \]

Calculating each pair:

\[ 35 - 33 = 2 \] \[ 31 - 29 = 2 \] \[ 27 - 25 = 2 \] \[ 23 - 21 = 2 \] \[ 19 - 17 = 2 \] \[ 15 - 13 = 2 \] \[ 11 - 9 = 2 \] \[ 7 - 5 = 2 \] \[ 3 - 1 = 2 \]

Each of these pairs equals \(2\). They create a total of \(9\) pairs from \(35\) to \(1\). Thus, we can calculate the total sum:

\[ 2 \times 9 = 18 \]

Therefore, the sum of the sequence is:

\[ \boxed{18} \]