Karl's preferences over hamburgers (H) and beer (B) are described by the utility function: U(H, B) =

Question:

Karl's preferences over hamburgers (H) and beer (B) are described by the utility function: U(H, B) = min(2H, 3B). His monthly income is I dollars, and he only buys these two goods out of his income. Denote the price of hamburgers by PH and of beer by PB.
a) Derive Karl's demand curve for beer as a function of the exogenous variables.
b) Which affects Karl's consumption of beer more: a one dollar increase in PH or a one dollar increase in PB?