Answer:
The length of the other side is 9 ft
Explanation:
To solve this we first have to know the formula to calculate the area of a rectangle 
 
a = area = 45 ft²
l = length 
w = width = 5 ft
 
a = l * w 
 
because we want to calculate the length, we will have to clear the l 
 
a = l * w 
l = a / w 
 
now we replace with the known values 
 
l = 45 ft² / 5 ft
l = 9 ft
The length of the other side is 9 ft