Question

if you are nothing try this 1+2+3+4+5+6+7+8+9​

Answer 1

Step-by-step explanation:

9+8+7+6+5+4+3+2+1

45

Answer 2

Step-by-step explanation:

it's a A. P

so, a =1

n=9

sn=n/2(a+l)

sn=9/2×10

sn=45