Determine the total number of quadruplets (A,B, C, D) of positive integers with A ≤ B ≤ C ≤ D ≤ 25, such that (A+B)*(C+D) is divisible by |A*D – B*C|, whenever A*D ≠ B*C.

__Note__: |x| refers to the

**absolute value** of x.

WAS:

**Tot= C(25,4)+25*C(24,2)+2*C(25,2)+25=20175 WRONG!**

**SHOULD BE:**

**
**__Tot= C(25,4)+25*C(24,2)+3*C(25,2)+25=20475 OK__

**1ST TERM: xyzv**

**2nd: xyyz**

**3rd : xxyy; xyyy; xxxy (one not taken in account)**

**4th: xxxx**

**12650+6900+900+25 = 20475 correct**

**THANK YOU , Charlie. After getting your result it took me 5 sec to locate the" missing 300" **

**look forward to a problem posted by me- based on this evaluation.**

** **

** **