Question

find three consecutive odd numbers whose sum is 21

Answer 1

let x,x+1,x+2 be the consecutive odd numbers.3x+3=21
3x=18
x=18÷3
x=6

Answer 2

let 1st number is X .second X+2; third X+4.....sum =
$x + x + 2 + x + 4 = 21 \ \\ 3x + 6 = 21 \\ 3(x + 2) = 21 \\ x + 2 = 7 \\ x = 7 - 2 = 5...$
there fore first number is X=5....second 7 and third is 9