The some of five different single digit whole numbers is 30. two of the numbers are one and eight if we multiply the same five numbers the product is 2520. what are the other three numbers?

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 :)