There is a clear cut reason why these questions were deleted while some other similar questions were accepted.
1)Your questions about finding the value of a algebraic equation was quite a new concept but was not much innovative. Hence, a few of them were accepted but later on when we discovered more of such questions, we deleted them as we want the members to post intellectual questions. Hence, please frame the mathematical word problems where the children can derive these equations from the given word problem. That shall be interesting to kids and they shall be greatly enhanced.
2)Your question about, "Which is the largest continent"? is a little controversial. Though Australia fulfills the condition for an island, it is not taken as an island due to its large size. Hence, Greenland is the largest island. You may argue over this but the truth is, there is no clear answer with regard to this. I have made it very clear in the guidelines that the members must not post controversial questions.
All these points were made clear by me in the guidelines. Kindly go through them again and post your questions accordingly.