Raingauge station 'X’ did not function for a part of a month during which a storm occurred, The storm produced rainfalls, of 80, 90 and 100 mm at three surrounding stations A, B and C_ respectively. ,The normal annual rainfalls at the stations X, A, B and C are respectively 880, 800, 880 and 1000 mm. Estimate the missing storm rainfall at station X.