Number of such words without both R together
= total possible words - total possible words with both R together
Number of such words start with A=2!5!−4!=36
Number of such words start with E=2!5!−4!=36
Number of such words start with FAE=2!3!−2=1
Number of such words start with FAM=2!3!−2=1
Number of such words start with FARE=2!=2
Number of such words start with FARMER=1
Total =77