Write 'em down in ascending order: 5,8,10,15,24,36,45,72.
Should now be apparent...
Question is
The following numbers are grouped in pairs so the product of each pair is the same
72 8 24 10 5 45 36 15
What number is paired with 10
36 45 24 15 72
Can the sum be got by either + - / or x or does it have to be the same for each one?