If 3 boxes can hold 27 books, how many boxes can hold 108 books?

Step-by-step explanation:

No of books that 3 boxes can hold = 27 books

No of boxes required =(3/27) * 108 = 3*108 / 27 =  3 *4 = 12

12 boxes are required

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