Help plis plis 18. Find the sum of (x + 3) and
(- x - 4).

Help plis

-1

Step-by-step explanation:

x+3-x-4

o-1

-1

x = -3

y = -18

step-by-step explanation:

to solve by substitution, substitute one variable and solve for the other. then substitute again to find the remaining variable.

x-1/3(3x-9) = -3 since y=3x-9 substittute y.

x-1/3(3x-9)=-3

x + x +3 = -3

2x+3=-3

2x+3-3= -3-3

2x=-6

x=-3

substitute again into y=3x-9

y=3(-3)-9

y=-9-9

y=-18

x-3y=4

step-by-step e