If type AB blood has type A in it, explain why a person with type A blood cannot have a transfusion of type AB blood?

They can't tranfuse because they will have an ABO incompatibility reaction. In an ABO incompatibility reaction, your immune system attacks the new blood cells and destroys them

If you have type AB you have both A and B antigens. Therefore you have B too that's why you can't only tranfuse with A after all you have to have to have both types.