Total no. of letters in the word EQUATION = 8 No. of vowels in the word (E, U, A, I, O) = 5 No. of consonants in the word (Q, T, N) = 3 When vowels & consonants occur together we make two groups, one is of vowels & second is of consonants. Arrangement of 2 groups = $\,{}^{2}P_2$ = 2! Arrangement of vowels in its group = $\,{}^{5}P_5$ = 5! Arrangement of consonants in its group = $\,{}^{3}P_3$ = 3! So, the required no. of words = 2! × 5! × 3! = 1440.