Cows, horses and dogs (Posted on 2008-10-20)

	Submitted by pcbouhid
Rating: 4.0000 (1 votes)
Solution:	(Hide)
The equation c*(c + h) = 120 + d reveals that d cannot equal 2, the only even prime number, since C would then also have to be 2, which is not a different number. So d must be odd, from which either c or h must equal 2, since the sum of the two would otherwise be even. Clearly, h must then must be 2, since c equals 2 would made the product even. Rewriting the equation, we get: c2 + 2c - 120 = d (c + 12)(c - 10) = d (c - 10) must equal unity in order for d to be a prime. Then: c = 11, h = 2 and d = 23 is the unique solution.

	Subject	Author	Date
	No Subject	Amanda Holmes	2022-04-18 11:11:02
	Puzzle Solution	K Sengupta	2008-11-21 05:05:24
	Answer	K Sengupta	2008-11-20 00:41:13
	Solution	hoodat	2008-10-26 23:51:19
	re: proof of uniqueness	pcbouhid	2008-10-21 07:39:21
	proof of uniqueness	Paul	2008-10-20 21:01:56
	re(2): Agreed - to rod	pcbouhid	2008-10-20 17:55:32
	re: Agreed	rod hines	2008-10-20 17:18:19
	Agreed	ed bottemiller	2008-10-20 16:38:48
	re: Odds are	rod hines	2008-10-20 15:14:16
	Odds are	ed bottemiller	2008-10-20 13:25:15
	computer solution	Charlie	2008-10-20 12:22:28
	Solution	ed bottemiller	2008-10-20 11:23:11