Explain how i solve these 5 math problems?

Question

Hi, I'm taking a class online and i don't have an instructor to help me go over it.. Plz help me with these sample problems provided, Explain step by step if you're able to.. Thnx...Best explanatin gets the 10 pts, it's been a while for me so i forgot this stuff

1. A triangle has sides of length 3a inches, 4b inches and 2a + 3 inches. What is the perimeter of the triangle?

2. Solve for x: 5x + 7 – 2x = 11 – 12x – 16

3. Simplify: – 3/4 (4/5) + 5/7 ÷ 5/3

4. Solve for x: 4 1/3 + x = 7

5. What is the total cost of buying 4 1/2 pounds of ground hamburger, which sells for $2.99 per pound?

Answer 1

1: Primeter is the sum of all sides, in this case 3a+4b+(2a+3)

                 combine like terms  3a + 2a +4b + 3 = 5a+2b+3

2) you have to get x by itself add or subtract from each side in order to isolate it. Whatever you do to one side you have to do to the other.

          combine like terms  5x + 7 - 2x = 11 - 12x - 16    

                                        5x - 2x + 7 = 11 - 16 -12x

           simplify                      3x + 7 = -5 - 12x

           now solve for x                        

add 12x to each side          12x + 3x + 7 = -5  + (12x - 12x)

      Combine like terms         15x +7= -5

Subtract -7 from each side    15x +7-7= -5 -7

                                            15x= -12

divide by 15 (each side)       15x/15= -12/15

                                              x= -12/15

3)   ah fractions....    gonna look this up

4) same as 2) but eaiser subtract 4 1/3 from 7

                x= 7- 4 1/3= 2 2/3

5) (2.99 x 4) + (2.99 x 1/2)