*Step 1*.

Open the parenthesis.

If in front of parenthesis there is a sign plus (#+#) or no sign at all you can open parenthesis as is, retaining all signs of each member inside.

If there is a sign minus (#-#) in front of parenthesis, all signs inside the parenthesis should be changed to opposite and then drop the parenthesis.

As a result, our expression will look like

#2x-3+7x^2-3+9x^2+2x#

*Step 2*.

Using *commutative law* (#a+b=b+a#) of addition and subtraction, regroup the members so that members with #x# in the same power are next to each other and so are free members (constants):

#7x^2+9x^2+2x+2x-3-3#

*Step 3*.

Using *distributive law* (#a*c+b*c=(a+b)*c#) consolidate members with #x# in the same power:

#(7+9)x^2+(2+2)x-6#

*Step 4*.

Final simplification:

#16x^2+4x-6#