3x (7+(-3)^2)÷3 i'm confused with the steps

You should use the acronym BODMAS which is Bracket, Of, Division, Multiplication, Addition and Subtraction
work out what is in the brackets first
because the 3 is negative in front of the -3 squared because negative (a negative and a positive makes a negative )
any number decided by itself equals 1
therefore the -3 at the beginning if the sum is divided by the three at the end of the sum
then evaluate the powers
the 3 squared becomes 9
lastly calculate what's inside the brackets and multiply

your working should look like this :

-3 (7+(-3)^2)÷3
-1(7-3^2)
-1 (7-9)
-1 (-2)
=2

Or like this:

-3(7−9)÷3
-3×−2÷3
6÷3
=2

B. 2 1/2 feet. multiply 2.5 inches by 12 to get thirty inches then divide by 12 to get 2.5 feet