 
 <translate> Out of the 400 emails, 1 / 4 * 400 = 100 emails were spam emails. The number of emails that were not spam emails is 400 - 100 = 300. 2 / 5 of the emails which were not spam were promotional emails, a total of 2 / 5 * 300 = 120 emails. If the rest of the emails were important emails, there were 300 - 120 = 180 important emails.
Therefore, the answer is 180. <hau> Daga cikin imel 400, 1 / 4 * 400 = 100 imel imel ne. Adadin imel ɗin da ba imel ɗin banza bane shine 400 - 100 = 300. 2 / 5 na imel ɗin da ba spam ba imel ne na tallace-tallace, jimlar 2 / 5 * 300 = imel 120. Idan sauran imel ɗin imel ne masu muhimmanci, akwai 300 - 120 = 180 imel masu muhimmanci. Saboda haka, amsar ita ce 180. 