@Srestha,look I worked out the example as per your suggestion.
Now to the same ques goes 3 answers.
Let the no's be 2x+1,2x+3,2x+5 respectively.So,
3(2x+1)=2(2x+5)+3
6x+3=4x+10+3
2x=10. x=5. And we want the third no therefore, (2x+5)=2*5+5=15.
Hence,15.