 
<translate> Bayyana tsarin tunani mataki-mataki sannan kuma amsar karshe. Cameron tana buga karatunta a laburaren makaranta kuma tana da takardun A4 guda 400. Idan kashi 40% na takardun ba su buga har zuwa ingancin da ta ke so ba kuma ta raba su a matsayin marasa inganci, ƙididdige jimlar adadin takardun da suka dace. <eng> Give the step-by-step reasoning process and then the final answer. Cameron is printing her thesis in the school library and has 400 A4 pieces of paper. If 40% of the papers did not print out up to her desired quality and she separated them as invalid, calculate the total number of valid documents. 