What will come Next? 19 9 29 8 39 __?

What will come Next? 19 9 29 8 39 __?

آگے کیا آئے گا؟ 19 9 29 8 39 __؟
Explanation

These are two series 

one is 9, 8, 7, etc 

sec is 9+10=19, 19+10=29, 29+10=39 etc

Correct Ans is 7