Lines a and b are parallel.
what is the value of x

Step-by-step explanation:

90 - 7x = 11 x

90 = 11x + 7x

90 = 18 x

90 / 18 = x

x = 5

angle addition postulate

2x=56

step-by-step explanation:

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