Answer:
Perimeter of rectangle = ⇒  feet
 feet
Step-by-step explanation:
Given:
Length of a rectangular sand box = 
Width of the box = 
Perimeter of a rectangle = 
where  represents length of rectangle and
 represents length of rectangle and  represents width of the rectangle.
 represents width of the rectangle.
Substituting values given for length and width.
Perimeter of sand box = 
Simplifying by adding fractions:
⇒   (Adding whole numbers and fractions separately)
 (Adding whole numbers and fractions separately)
⇒   feet
 feet
 Whole number 8 can be written as 
⇒   feet
 feet
To add fractions we take LCD for the denominators 3,4,1.
LCD for 3 and 4 = 12 as its the least common multiple of 3,4,1.
Making denominators =12 by multiplying numerator an denominator with the corresponding numbers
⇒   feet
 feet
⇒   feet
 feet
Then we simply add numerators.
⇒   feet
 feet
⇒   feet
 feet 
⇒   feet
 feet
⇒   feet
 feet
Writing fraction as a mixed number by dividing 218 by 12 and writing quotient as whole number and remainder as numerator with divisor as denominator.
⇒  feet
 feet
Simplifying fractions to simplest form.
⇒  feet
 feet
Perimeter =⇒  feet  (Answer)
 feet  (Answer)