Question

The perimeter of a square JKLM is 48 units ..what is the x?

Answer 1

we know that

The perimeter of a square is equal to

$P=4b$

where

b is the length side of a square

In this problem we have

$b=(x+3)\ units\\P=48\ units$

substitute in the formula

$48=4(x+3)$

Solve for x

$12=(x+3)$

$x=12-3=9\ units$

therefore

the answer is

The value of x is $9\ units$

Answer 2

P=4*a, where P - perimeter, a - length of one side of the square.
if a=x+3 and P=48, then 4(x+3)=48;
x=9.
Answer: 9 units.