We need help with a math equation?

I assume you are solving for x, since there's no instructions. Just remember order of operation, then move x to one side (isolate it).

7x - 29 - 21x = 3 - (12 - 2x)

I combined like terms and did the distributive property. Think of the "-" on the right side as a -1.

-14x - 29 = - 9 + 2x

Now solve for x.

-14x = 20 + 2x

-16x = 20

x = - 20/16, -5/4, or - 1.25

On the right hand side of the equation there is a bracket

The minus sign in front of the brackets says that everything inside the bracket is to be multiplied by -1

The right hand side becomes 3 - 1 times 12 -1 times - 2x

minus times a plus gives a minus but a minus times a minus gives a plus

Now we have

7x - 29 -21x = 3 - 12 + 2x.............now gather like terms remembering that if any item crosses the equals sign then + and - signs change

-29 -14x = -9 + 2x

-29 + 9 = 2x + 14x

-20 = 16x

x = -20/16 = -5/4 = - 1 and 1/4

PS

JUST TO GIVE A BIT MORE HELP

Do not forget the signs when plugging in -1and 1/4

-1.25 x7 -29 + 21 x 1.25 (two minuses here make a big plus)

= 3 - 12 - 2 x 1.25(Here it changws to a plus first then back to a minus because of the bracket)

It does work out

7x - 29 - 21x = 3 - (12 - 2x) [distribute the negative on the RHS]

7x - 29 - 21x = 3 - 12 + 2x [combine like terms on both sides]

-14x - 29 = -9 + 2x [combine like terms]

-20 = 16x [divide both sides by 16]

-20/16 = x [simplify]

-5/4 = x

x = -5/4 OR x = -1.25

voila