Consider input-output model: input matrix: a= r 0.05 0.33 0.19 0.25 0.10 0.38 0.34 1 0.12 0 final-demand vector: d= r 1800 200 900 1) explain economic meaning of the elements 0.25, 0, and 900. (3 points) 2) explain the economic meaning of the second-column sum. (3 points) 3) write out the specific input-output matrix equation for this model. (2 points) 4) solve the model by any method. (8 points) 5) describe in words what your solution mean. (4 points) 6) write out comparative-static derivatives in the form of 7.23" on page 174 in the textbook. (2 points) 7) what does the partial derivative of xı with respect to d2 mean? (2 points)