As you know what 100% is (810) the best thing to do is to find what 30% is.
The best way to do this is to find 10% then multiply it by 3.
810/10= 81
81*3= 243
You've then got to add these two (810 and 243) together
810+243= 1053
As you've got an increase, this then means that you have to add this to the original number
810+1053= 1863
Therefore, there are now 1863 songs.
Hope this helps :)