Question 139123
First of all, you need to know the formula for a rectangle's perimeter. 
Perimeter= 2length + 2width

You are given: 
length= 12 meters
perimeter= 38 meters

-->Substitue in your information:
38= 2(12) + 2(width)

-->Simplify: 14 = 2(width)

-->Divide 2 on both sides: 7 = width

Therefore, the width of the rectangle is 7 meters.