Evan is making ham and cheese sandwiches for a party. Each sandwich is made from 1 bread roll, 1 cheese slice and 1 ham slice.
He has bought bread rolls in packs of 9, cheese slices in packs of 6 and ham slices in packs of 8.
When Evan has finished making the sandwiches, there is nothing left in any of the packs.
What is the minimum number of packs of each ingredient that Evan could have bought?