Question 391588
Let's make them one letter, the "th" letter. 4!=24
Let's make them one letter, the "ht" letter. 4!=24
24*2=48 ways they are not separated by a letter.
5!=120 possible arrangements of the word "think".
120-48=72 ways you can arrange "think" so the t and h are seperated by at least one letter.
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Ed