How do you determine if numbers are co-prime? Check to see if the is equal to one. Since we're duplicating tasks willy-nilly, lift code from , (or in this case, just use the builtin).
say .raku, ( [gcd] |$_ ) == 1 ?? ' Coprime' !! '' for [21,15],[17,23],[36,12],[18,29],[60,15],[21,22,25,31,143]