Ranked ladder

I was #9 on the ranked ladder but got demoted to #10 by someone who has the same number of RP as me. even though i am #10 i am in the tier 2 area of the ranked ladder. why have i lost my spot of #9 to someone who has the same number of RP earned as me, and why am i no longer in the ladder champion top 10 even though i am literally ranked #10.