Step-by-step explanation:
1) If we have 1/2 OWLs of Snicker bars, then number of items or Snicker bars :
1 OWL = 7 items (given)

We have 3.5 Snickers bars.
2) If we have 100 OWLs of pencils, then number of items or pencils :
1 OWL = 7 items (given)

We have 700 pencils.
3) If we have 2 OWLs of iron atom, then number of iron atoms :
1 OWL = 7 items (given)
of iron
We have 14 atoms of iron.