Write a system of linear equations in three or four variables to solve Exercises 47–50. Then use matrices to solve the system.

The bar graph shows the number of rooms, bathrooms, fireplaces, and elevators in the U.S. White House.

Combined, there are 198 rooms, bathrooms, fireplaces, and elevators. The number of rooms exceeds the number of bathrooms and fireplaces by 69. The difference between the number of fireplaces and elevators is 25. If the number of bathrooms is doubled, it exceeds the number of fireplaces and elevators by 39. Determine the number of rooms, bathrooms, fireplaces, and elevators in the U.S. White House.

150 125 100 75 50 25 The U.S. White House by the Numbers W Rooms Bathrooms X ... Fireplaces *************.. Elevators Z