Question

I'm lazy and dont feel like doing math myself. So pls help me!

Answer 1

Answer:

55

Step-by-step explanation:

$\frac{n(n + 1)}{2} \\ n = 10 \\ substitutig \\ \frac{10(10 + 1)}{2} \\ \\ \frac{10(11)}{2} \\ \\ \frac{110}{2} = 55$