Show that the set of letters needed to spell “CATARACT” and the set of letters needed to spell “TRACT” are equal.

For “CATARACT”

Distinct letters are

{C, A, T, R} = {A, C, R, T}

For “TRACT”

Distinct letters are

{T, R, A, C} = {A, C, R, T}

As we see letters need to spell cataract is equal to set of letters need to spell tract.

Hence the two sets are equal.