math
posted by Cole .
Hector owns science fiction novels, coming c books, and mystery novels. He has half as many science fiction novels as comic books and he has three times as many mystery novels as comic books. If he owns a totals of 54 books how many of those book are science friction novels?

X Comic books.
X/2 Science fiction.
3X Mystery novels.
X + X/2 + 3X = 54,
Multiply both sides by 2:
2X + X + 6X = 108,
9X = 108,
X = 12,
X/2 = 6 Science fictions novels.