Answer
$-192$
Work Step by Step
$\sum_{i=1}^{24} (17-2i)=-2 \times \sum_{i=1}^{24} i+\sum_{i=1}^{24} (17)$
$=(-2) \times \dfrac{(24) \times (24+1)}{2}+17 \times (24)$
$=(-2) \times \dfrac{(24) \times (25)}{2}+17 \times (24)$
$=-600+408$
$=-192$