There are 4 sides so add 4 sides
3x-4+3x-4+2x+3+2x+3=78
Combine like terms
10x-2=78
Add 2 to each side of the equation
10x=80
Divide by 10
X=8
Enter x into equation
3(8)-4=20
2(8)+3=19
Multiply by 2
20 x 2= 40
19 x 2 = 38
40 +38 =78
Side 1- 20
Side 2- 19
Side 3- 20
Side 4- 19
