SBI Junior Associates Model Paper 2

A postman was returning to the post office which was in front of him to the north. When the post offfice was 100 metres away from him, he turned to the left and moved 50 metres to deliver the last letter at shantivilla. He then moved in the same direction for 40 metres, turned to his right and moved 100 metres. How many metres away he was now . from the post office?