if i do that, the enemy appears much at once directly and i think it because the mod == "0"

i see... you want to summon an enemy when myscore %100==0 you should put checking only when score was added myscore++; if(myscore %100==0) x++;

The way azazeel gave will work. It is always best to check these type values (scores, lives, health, etc) immediately after their values are changed. If not done immediately, the comparison may remain true for multiple act cycles and you will be doing the action required unnecessarily multiple times. If doing things like working with images or adding new actors into the world, you could end up with your project lagging, or even worse, crashing.