3/17 x 17/21 in the lowest terms

Explanation:

357 is divisable by 51

is the lowest term. You can also see that because there is a 17 on top and a 17 on bottom so they cancel. You're left with 3/21 which reduces to

martians or other types of aliens represent a unique fear as opposed to zombies. vampires and other types of monsters.   in most sci-fi stories, aliens come from other worlds and have different or more advanced technology.   abductions and experimentation on human bodies that involve these technologies, or the use of these technologies against human beings and the use of unknown "powers", are a type of fear that's different from that of other types of monsters.