engel - essentially just demand curves, except w/ respect to income  

• axes changes to income and just 1 good
• normal good - increased income >> increased consumption
• inferior good - increased income >> decreased consumption
• take demand curve C = (4/5) (I/P_C) for instance
  • C changes w/ I >> linear relationship
  • I is independent variable, C is dependent
  • engel curve would be linear line

• income consumption curve for an inferior good
• consumption of good 1 decreases w/ increasing income by the 3rd budget line >> good 1 is an inferior good
• consumption of good 2 increases w/ increasing income >> normal good