3. A solution of a linear equation in three variables is an ordered triple. ( x, y, z) that makes the equation true. The solution of a system of equations in three variables is an ordered triple that makes all of the equations in the system true. T

4. To show that ( 3/2, -4, 3) is a solution of the following system, we substitute into all three equations. 4x – 2y – 3z = 5 -8x –y + z = -5 2x + y +2z = 5

5. Solve these systems x + 2y – z = 5 2x – 4y + z = 0 3x + 2y + 2z = 3

6. Solve these systems x + 2y - z = -8 2x – y + z = 4 8x + y + z= 2

7. Solve these systems x + y +2z = 1 x – y + z = 1 2x + 3 z= 2

8. Solve: x + y -z = 2 x – y -2z = 2 2x + 3 y + z= 9

9. The sum of three numbers is 57. The second is 3 more than the first. The third is 6 more than the first. Find the numbers.

10. In triangle PQR, the measure of angle Q is three times the measure of angle P. The measure of angle R is 30 0 greater than the measure of angle P. Find the angle measures.

11. Sawmills A, B and C can produce 7400 board feet of lumber per day. A and B together can produce 4700 board feet while B and C together can produce 5200 board feet. How many board feet can each mill produce by itself?