In a pure exchange economy with two goods, G and H, the two traders have Cobb-Douglas util- ity functions. Amos' utility is Ua = (Ga)"(Ho) 1-a and Elise's is U. = (G.) B(H.)] -B. What are their marginal rates of substitution? Between them, Amos and Elise own 100 units of G and 50 units of H. Thus, if Amos has G, and H., Elise has Go = 100 - G. and He = 50 - H.. Solve for their contract curve