here if u take statement 1 alone the u have info about linda i.e. the percentage of boxes linda packed.
let us consider total no. of boxes be x
therefore, linda has .3x
its not giving any infor about pat and robert but r(robert) + p(pat) = .7
hence insufficient.
take statement 2 :
r = 10 + p
it does not tell anything about the ratio r/p.
hence insufficient.
take both the statements together:
l=.3x and p + t = .7x
also r = 10 + p ---------> (1)
also we can write l + p + t = x(total no of boxes by all three). ------> (2)
put (1) in p+t = .7x
we get 2p + 10 = .7x
now put l=.3x and p = 10 + t in (2)
we get 2p+10 = .7x . now this is the same equation as above. but we have 2 variables and 1 equation so we cannot solve it for a unique value.
hence insufficient.
In short even if u take both the statements together there is no enough info to solve it for unique values.
Thus E is the correct answer.