Collection of multiple supplies tied together which are non-detachable are called composite. A primary supply is one of these. The tax rate on such composite supplies is the same as on the primary supply.
The term “Mixed Supply” means at least two different sources of services or goods and these are detachable as they are not bound together naturally. The tax rate on these supplies should be higher than that would apply to any of those supplies if they were sold at the same price.