- elastic: when a change in price causes a much larger change in quantity demanded
 - inelastic: when a change in price causes a small change in quantity demanded
 - unit elastic: when the % change in quantity demanded = the % change in price
 - technical مفيد: useful
 - revenue المال الحقيقي: total income from a given source or product
 - expenditures: things you pay for
 - inverse عكس: opposite; the other way
 - delayed تاخر: pushed back in time
 - hardship مشكله: a problem
 - adequate كافي: so-so, alright (a grade of C)