The word Threty is misspelled against Thretty, an adjective meaning "Thirty."
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Thretty has double "tt" is mispronounced as "t"
Remember double 'TT' in between the strings thre & y which should not be misspelled with single 'T'
Wrong Spelling: thre-t-y
Correct Spelling: thre-tt-y
Explore spell check of Thretty to spell without errors.