How many £ difference is the poverty line of a single adult with no dependent children  compared to couples with no dependent children?
return a single adult with no dependent children  ;return couples with no dependent children  ;return poverty line in  £ of #1 ;return poverty line in  £ of #2 ;return the  difference of #3 and  #4
['select', 'select', 'project', 'project', 'arithmetic']