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x = 0, x = 4

Step-by-step explanation:

12x - 21 = 5x + 7(x - 3)

First, foil out the right side --> 5x² - 15x + 7x - 21, which simplifies down to 5x² - 8x - 21.

Move the 12x - 21 to the right side by subtracting --> 0 = 5x² - 20x.

Factor out a 5x --> 0 = 5x(x - 4)

If you want to solve for x, set 5x = 0 and x - 4 = 0.

For 5x = 0, divide both sides by 5 to isolate the x --> x = 0/5, which simplifies down to x = 0.

For x - 4 = 0, add 4 to both sides to isolate the x --> x = 0 + 4, which simplifies down to x = 4.

Plug the values back into the original equation to check if it works

12(0) -21 = 5(0) + 7((0) - 3) --> -21 = -21

12(4) - 21 = 5(4) + 7((4) -3) --> 27 = 27

Hope this helps!

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

24

step-by-step explanation:

the graph shows 30% of students walk. 80 students were questioned, so the number that said they walk is

30% × 80 = 0.30 × 80 = 24