2x + y - z=-7
5y- z=1
3z = 12
solve the 3x3 system

Step-by-step explanation:

3z = 12

z = 4

5y - 4 = 1

5y = 5

y = 1

2x + 1 - 4 = -7

2x - 3 = -7

2x = -4

x = -2

(-2, 1, 4)

c.

step-by-step explanation:

because first you have to add the 4x, 9x, and the 7x together and you get 20x and then you add the last numbers up and you get 5and then you put the subtraction sign in there and that's how you get the answer.

answer: the angel abc is 30°,and the abc is a triangle where the angel bac is 90°

so ac is the half of 24=12ft,and from the pythagorean theorem we find ba

ba=√bc^2-ac^2=√576-144=√432=12√3ft

so bac is 12+12√3=12(1+√3)ft