1+8+x+y+z=30
9+x+y+z=30
x+y+z=21
1*8*x*y*z=2520
8xyz=2520
xyz=315
2+19=21 19 can't be made with single digit numbers:
not 2
3+9+9=21 9 can't be used twice:
not 3
4+8+9=21 8 is one of the other numbers and 4 can therefore not be used:
not 4
5+7+9=21 and 5*7*9=21
The other 3 numbers are as follows: 5, 7, 9
Hope this helps :)