Keith spent 1 5 of his money on a story book. He gave $46.80 to his brother and had 1 2 of his money left. How much monry did he havr left?

1 answer

Let X be the money Keith had.
Keith spent X/5 on a story book.
Keith gave $46.80.
Keith had X - X/5 - $46.80 = X/2 left.
Multiplying both sides by 10 gives 10X - 2X - 468 = 5X.
Combining like terms gives 3X - 468 = 0.
Adding 468 to both sides gives 3X = 468.
Dividing both sides by 3 gives X = 156.
Thus, Keith had $156/2 = $<<156/2=78>>78 left. Answer: \boxed{78}.