Python | Percentage increase in the total surface area of the cuboid

Given a cuboid of length L, breadth B and Height H, the task is to find percentage increase in the total surface area of the cuboid if length, breadth and height are increased by fixed percentages. 
Examples:

Input :
L = 20, B = 30, H = 50, l = 10 %, b = 12 %, h = 15 %
Output :
26.97 %

Input :
L = 40, B = 60, H = 15, l = 5 %, b = 7 %, h = 12 %
Output :
14.88 %

Code : Python code to find the increase in the total surface area of the cuboid. 

Python3

# Function to return the percentage increase
# in the total surface area of the cuboid
# Total surface area of a cuboid = 2(L * B) + (L * H) + (B * H)
def increaseIntsa(L, B, H, l, b, h):
    oldsurfacearea = 2*((L * B) + (L * H) + (B * H))
    newsurfacearea = 2*((L + (L * l * 0.01))*(B + (B * b*0.01)) +
                        (L + (L * l * 0.01))*(H + (H * h*0.01)) +
                        (B + (B * b * 0.01))*(H + (H * h*0.01)))
    increase = (newsurfacearea - oldsurfacearea)
    increasepercent = (increase / oldsurfacearea) * 100
    return(increasepercent)

# Cuboid dimensions
L = 20
B = 30
H = 50

# percentage increase
l = 10
b = 12
h = 15
print(increaseIntsa(L, B, H, l, b, h), "%")

Output : 

26.974193548387092 %

 Time Complexity: O(1)

Auxiliary Space: O(1)