<span><span><span><span><span>(<span>5+4</span>)</span><span>(2)</span></span>+6</span>−<span><span>(2)</span><span>(2)</span></span></span>−1</span><span>=<span><span><span><span><span>(9)</span><span>(2)</span></span>+6</span>−<span><span>(2)</span><span>(2)</span></span></span>−1</span></span><span>=<span><span><span>18+6</span>−<span><span>(2)</span><span>(2)</span></span></span>−1</span></span><span>=<span><span>24−<span><span>(2)</span><span>(2)</span></span></span>−1</span></span><span>=<span><span>24−4</span>−1</span></span><span>=<span>20−1</span></span><span>=<span>19</span></span>
You can put the -4 and -9 together and put it at the end to make the new sequence 4-13 which would leave you with -9