Solve for x, y, z: {4x – y = 4} {y – 5z = –12} {5x + z = 19} Then evaluate: x + y + z =

Question

(A) 161/3

(B) - 43

(C) 15

(D) 57

(E) none of these

Answer 1

{4x – y = 4} {y – 5z = –12} {5x + z = 19}=

4x - y = 4 (1) and 5x + z = 19 (2).

(1 ) - (2): - x - y - z = - 15; so, x + y + z = 15

Answer is (C)