 
 <translate> There are 109 fifth graders + 115 sixth graders + 118 seventh graders = 342 students going on the trip. There are 4 teachers + 2 parents = 6 adults going on the field trip for each grade. There are 3 grades going, so 3 grades x 6 adults / grade = 18 total adults going on the trip. There are 342 students + 18 adults = 360 people going on the trip. So, 360 people / 72 seats = 5 buses.
Thus, the answer is 5. <hau> Akwai dalibai 109 na aji biyar + 115 na aji shida + 118 na aji bakwai = dalibai 342 da ke tafiya. Akwai malamai 4 + iyaye 2 = manya 6 da ke tafiya a kowane aji. Akwai maki 3 da suke tafiya, don haka maki 3 x manya 6 / maki = 18 duka manya da suke tafiya. Akwai dalibai 342 + manya 18 = mutane 360 suna tafiya. Don haka, mutane 360 / kujeru 72 = bas 5. Saboda haka, amsar ita ce 5. 