Question

The first term of an A.P. is 5, the last term is 45 and sum is 400. Find the
number of terms and the common difference.​

Answer 1

Step-by-step explanation:

a=5

tn=45

Sn=400

n=?

d=?

since

Sn=n/2(t1+tn)

Answer 2

Answer:

now,

an = a+(n-1)d

45=5+(16-1)d

45-5=15d

40/15=d

d=2.6