Consider a consumer whose utility is given by u(x, y) = x + y. She

spends her income, given by I=10, on two consumption goods, x and y,

the prices of which are given, respectively, by p_x= 2 and p_y=1 . The

government is levying a (per-unit) tax on y, denoted by t. Characterize

the excess burden as a function of t.