Question

sum of odd numbers equal to 30

Answer 1

29+1 = 30
27+3 = 30
25+3+1+1 = 30

you can take as many as you want!:))

Answer 2

According to the formula n(n+1)/2;
n is the number of odd numbers you have added
so ,
n²+n=30
n²+n-30=0
⇒n²+6n-5n-30=0
⇒n(n+6)-5(n+6)=0
⇒n=5;n=-6
And n cannot be negative
so 
n=5
Number of odd numbers is 5 
So the odd numbers are
1+3+5+7+5+9
This the method of
 Arithematic progression