The equation for the perimeter of a square is P=4s (s=the length of each side)
So we can plug in the perimeter and solve for the side
48=4s
s=12 (divide both sides by 4)
The equation for the area of a square is A=s^2 or A=s*s
We can plug in the value for each side to find the area
A=12*12
A=144 units
Hope this helps!