Is pqr = r?
pqr - r = 0
r ( pq - 1) = 0
r = 0 OR pq = 1
For the equation to hold, either:
(1) r=0 and pq could be anything, OR
(2) pq=1 and r could be any number
If we prove (1) or (2) then the answer to the question is YES!
Statement 1: pqs = s tells us either s=0 or pq=1. If s=0 then pq could be any number. it tells nothing about r also. INSUFFICIENT!
Statement 2: pqm = m is the same as Statement 1. INSUFFICIENT!
Impossible is nothing to God.