Three identical single phase 2400/240 v , 50 Kva transformers are connected to work as 3 phase 4160/

Three identical single phase 2400/240 v , 50 Kva transformers are connected to work as 3 phase 4160/240v transformers. each transformer has Req = 1.42 ? Xeq 1.82 ?

a) state how you connect the transformers

b) if the three phase transformers supplied a load of 70 kva at 240v and a 8.0 Power factor lagging. calculate the required primary voltage.

c) calculate the efficenty neglecting core loss