Question

(7-m)(7-n)(7-p)(7-q)=4 , then m+n+p+q=?

Answer 1

M=3
N=6
P=6
Q=6

Substitute these values in your Question ,u will get answer is 4

So m+N+p+q=3+6+6+6
=21

Answer 2

Given,
(7-m)(7-n)(7-p)(7-q) = 4
and factors of 4 = 2*2*1

So that we have to get the 4 by multiplying these factors four times
2*2*1*1 or 2*1*2*1 or 1*2*1*2
 So the values of m,n,p,q will be 5, 5, 6, 6  or  5,6,5,6  or  6,5,6,5 then only we can get the 2*2*1*1
Note that values of factors  can be in  any order like 2,1,2,1 or 1,2,1,2 or 2, 2, 1, 1.

m + n + p+ q = 5 + 5+ 6+ 6 = 22.

Example:-LHS: (7-5)(7-5)(7-6)(7-6)

= 2*2*1*1 = 4 
 
= R.H.S