As long as the world equilibrium relative price lies within the interval set by the pre-trade national equilibrium relative prices of two trading countries, each country _____ gains from trade.

Refer to the figure above. Assuming that the market consists of only these two consumers, what is the market demand for pens when the price is $4?

A) 15 units B) 25 units C) 40 units D) 65 units

Refer to the scenario above. What is the absolute value of Gary's arc elasticity of demand for shirts?

A) 1.2 B) 2.14 C) 3.26 D) 5