Question

calcule:
$\frac{n \times (n - 3)}{2}$
para N = 10​

Answer 1

$\frac{n \times (n - 3)}{2} = \\ \frac{10 \times (10 - 3)}{2} = \\ \frac{10 \times 7}{2} = \\ \frac{70}{2} => 35$