Alright! So, before we solve this we need to know the properties of a square. A square has 4 interior right angles and the sides are congruent (equal). So, for part a, we need to set the two statements equal to each other (which is where the algebra comes in).
6x + 5 = 8x - 3
*subtract 6x from both sides*
5 = 2x - 3
*add 3 to both sides*
8 = 2x
*divide by 2 on both sides*
x = 4. That's the answer to part a.
For part b, all you need to remember is that all 4 sides of a square are equal. So, all you need to do is find the length of 1 side and then multiply by 4.
6(4) + 5 = 29.
So 29 is the measurement of one side. Then, 29 * 4 = 116.
The perimeter is 116.
