An economy has three goods -- electricity, gravel, and timber. In the production process the amount required to produce 1 unit of each is given as follows. To produce 1 unit of To produce 1 unit of To produce 1 unit of Electricity Gravel Timber Electricity 21 .10 .23 Gravel .20 .31 25 .34 Timber 21 .18 You find the production schedule that meets the external demand for 100 units of electricity, 87 units of gravel, and 110 units of timber. What is the matrix equation describing the production schedule?