Some one help

x =  8 hours

Step-by-step explanation:

add up all the parts,

the teachers spends 24 hours in a day to do 18 parts

there are 2 parts for grading per day, we need to solve for 3 days so 3*(parts) or 6 parts for grading

use ratio to solve for x,

24 hrs          x (hours)

 =  

18 parts            3*(2 parts)

solve for x = (24 * 6 )/ 18 = 8 hours

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