20. solve –4(6x + 3) = –12(x + 10). a. x = 9 b. x = 2 c. x = –5 d. x = 5

A. x = 9

Step-by-step explanation:

Note the equal sign, what you do to one side, you do to the other.

First, distribute -4 to all 6x and 3, as well as -12 to x and 10.

-4(6x + 3) = (-4 * 6x) + (-4 * 3) = -24x - 12

-12(x + 10) = (-12 * x) + (-12 * 10) = -12x - 120

-24x - 12 = -12x - 120

Isolate the variable, x. Add 12 & 12x to both sides.

-24x (+12x) - 12 (+12) = -12x (+12x) - 120 (+12)

-24x + 12x = -120 + 12

Simplify. Combine like terms.

(-24x + 12x) = (-120 + 12)

-12x = -108

Isolate the variable, x. Divide -12 from both sides.

(-12x)/-12 = (-108)/-12

x = 9

A. x = 9 is your answer.

Check: Plug in 9 for x in the equation:

–4(6x + 3) = –12(x + 10)

-4(6(9) + 3) = -12(9 + 10)

-4(54 + 3) = -12(19)

-4(57) = -12(19)

-228 = -228 (True)

~

$4034.40

the perimeter of the field is the sum of the lengths of the four sides:

47 yd + 158 yd + 47 yd + 158 yd = 410 yd

the cost of 3 ft (1 yd) of fence is 3×$3.28 = $9.84.

so the cost of jake's wood perimeter fance is

(410 yd) × ($9.84 /yd) = $4034.40