To find how many songs she has in total you would need to multiply 9x4 which will equal 36. Now you multiply 9x4 because she has 4 music files which have 9 songs in each so 9+9+9+9= 36. So now you need to find how many times 7 goes into 36 to find this you divide 36 by 7 which will give you 5 times maximum. 7x5= 35, you cant use 6 because 7x6 = 42 which is too much. So you know now that 7x5= 35 and you have 36 songs total so now you have to subtract : 36-35 which will give you 1. You have one song left over :)
OKay well first you have multiply, so 4 x 9 = 36. Now you have to try to find how many songs will fit into 7 groups. So 5 is the maximum number for each group. cause 5 x 7 equals 35. But if you try to do 6, 6 x 7 which equals 42 which is too much, so 5 in each group. Now we have to try to find how many are left over, so we subtract, 36-35 equals 1. So you have one song over.