A person has total money was 50.he spent 20 rupee on lunch that he has now 30 rupee.then he eat a chip that cost was 15 then he was 15 rupee now.then he eat a ice cream which cost 9 rupee then he now only 6 rupee.then he eat toffee which cost 6 then he had no rupee ( 0 rupee) . friends draw a diagram in center total money left side his balance right side he spend money on..then u total both side valance and spend money. balanced was 51 and spend was 50 why friends ???