M is the point of intersection of L1 & L2
⇒2λ−1=2μ−1,3λ−1=3μ−1,6λ−3=9
⇒λ=2=μ
⇒M(3,5,9)
Now let point P be (2K−1,3K−1,6K−3) on L2
such that PM=7
⇒(2K−4)2+(3K−6)2+(6K−12)2=7
⇒49K2+196−196K=49
⇒K2+4−4K=1
⇒K2−4K+3=0
⇒K=1,3
So points P & Q are (1,2,3) & (5,8,15)
So sum of all co-ordinates of P & Q =34