Question 321336
use the -z in the 1st eqn to eliminate the z terms in the 2nd and 3rd eqns


multiply 1st by 5 and add to second ___ (A) ___ 4x + 7y = -2


multiply 1st by 4 and add to 3rd ___ (B) ___ 7x + 9y = -10


multiply (A) by -7 and add to 4 times (B) ___ -13y = -26 ___ y = 2


substitute to find x ___ 4x + 7(2) = -2 ___ x = -4


substitute to find z ___ (-4) + (2) - z = 3 ___ z = -5