Question

5+ 10+15+20+25........+90​

Answer 1

Answer:

855

Step-by-step explanation:

a=5 tn=90

tn=a+( n-1)d

90 = 5+(n-1)5

90 = 5+5n -5

90 =5n

n=18

s=n[2a+(n-1) d]

put all the value

9[10 +85]

9 x 95

855