The problem to solve is:

(-12x -12)/((x+3)(x+4)(x-5))

Multiply x and 12

Multiply x and 1

The x just gets copied along.

x

12*x evaluates to 12x

Because of the minus sign

12x becomes - 12x

-12*x-12 evaluates to -12x-12

x+3 evaluates to x+3

x+4 evaluates to x+4

Multiplying x+3 by x+4 is a classic Algebra problem. Here, you are trying
to multiply two binomials together (two expressions that each contain two terms).
Your book might call this finding the "Product of Two Binomials".

To work this problem, we'll use the "F.O.I.L." method. F.O.I.L. stands
for First, Outer, Inner, Last.

First, we'll multiply the two First terms, the x and x together.

Multiply x and x

Multiply the x and x

Multiply x and x

Combine the x and x by adding the exponents, and keeping the x, to get The answer is  x × x = Second, we'll multiply the two Outer terms, the x and 4 together.

Multiply x and 4

Multiply x and 1

The x just gets copied along.

x

x × 4 = 4x

Third, we'll multiply the two Inner terms, the 3 and x together.

Multiply 3 and x

Multiply 1 and x

The x just gets copied along.

x

3 × x = 3x

4x combines with 3x to give 7x

Lastly, we'll multiply the two Last terms, the 3 and 4 together.

Multiply 3 and 4

1

3 × 4 = 12

(x+3)*(x+4) evaluates to x-5 evaluates to x-5

Multiply by x-5

we multiply by each term in x-5 term by term.

This is the distributive property of multiplication.

Multiply and x

Multiply the and x

Multiply and x

Combine the and x by adding the exponents, and keeping the x, to get The answer is   × x = Multiply and -5

Multiply and 1

The just gets copied along.

The answer is   × -5 = Multiply 7x and x

Multiply the x and x

Multiply x and x

Combine the x and x by adding the exponents, and keeping the x, to get The answer is  7x × x =  combines with to give Multiply 7x and -5

Multiply x and 1

The x just gets copied along.

x

7x × -5 = -35x

Multiply 12 and x

Multiply 1 and x

The x just gets copied along.

x

12 × x = 12x

-35x combines with 12x to give -23x

Multiply 12 and -5

1

12 × -5 = -60

(x+3)*(x+4)*(x-5) evaluates to Sorry, at this time the divisor may be a monomial AT MOST (e.g. contain only 1 term).
The answer below IS NOT correct.
(-12*x-12)/((x+3)*(x+4)*(x-5)) evaluates to -12x-12