Question

three no are in AP. and their sum is 21 ; then the middle term is​

Answer 1

let a,b and c be the numbers

2b=a+c

a+b+c=21

2b=21-b

3b=21

b=7

Answer 2

let the three consecutive number be (a-d), a, (a+d)

where a is middle number

sum is 21

hence ,

(a-d)+a+(a+d) = 21

a-d+a+a+d = 21

3a = 21

a = 7

so middle term is 7