請教一下 應該是公共財的問題 - 經濟

The price to drive in a freeway is zero at all times
of the day. This price establishes equilibrium at 3 a.m.
but is too low to establish at 5 p.m. There is a shortage of
freeway space at 5 p.m.

a) Graphically show and explain how carpooling may eliminate
the shortage and explain your answer.
b) Graphically show and explain how building more freeway may
eliminate the shortage and again explain your answer.

我想請問一下 這一題是要用什麼去看比較好
是公共財 還是 限高價 還是???
有點看不懂這一題 請高手幫忙一下^^

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