In the economy of Mungo, discussed in your workbook, there is a third person called Ike. Ike has a red income of 56 and a blue income of 10. (Recall that blue prices are 1 bcu [blue currency unit] per unit of ambrosia and 1 bcu per unit of bubblegum. Red prices are 2 rcus [red currency units] per unit of ambrosia and 6 rcus per unit of bubblegum. You have to pay twice for what you buy, once in red currency, once in blue currency.) If Ike spends all of his blue income, but not all of his red income, then it must be that: