Hey there!!
Formula to find the perimeter of a rectangle
= 2 ( Length + Breadth )
Length = 5 feet
Perimeter = 15 feet
Let's take breadth as ' x ' feet
Now, plug in the values
2 ( 5 + x ) = 16
Use the distributive property
10 + 2x = 16
Subtract 10 on both sides
2x = 6
Divide 2 on both sides
x = 3
Hence, breadth = 3 feet
Hope my answer helps!