The answer depends on what you are actually asking.
If you mean 54 ft x the length of 10 legs + the length of 20 arms, then you can express it as "54 ft x (the length of 10 legs + the length of 20 arms)".
If you know the actual length of each leg & each arm, then you could add the lengths of each leg & the lengths of each arm & and you could maken an expression such as: "54 ft x (TL leg ft + TL arm ft)
If you know the average leg length & average arm length, then you could maken an expression such as: "54 ft x (10 x aver leg len + 20 x aver arm len)
Lastly, if you know such lengths, you could multiple 54 x TL length of the appendage to arrive at total square feet number.
10 feet
One story is approximately 10 feet, so 20 stories are approximately 200 feet.
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The wave base (the depth at which water moves) would be about 10 feet, or 1/2 the wavelength.
The length of the swimming pool is 20 feet Check: 20 times 10 = 200 square feet
He had 20 arms
The area of 20 feet times 10 feet = 200 square feet.
20 by 2 = 40 40 by 10 feet = 400 feet.
You have very long arms if it is 20 metres long! 20 metres = 65.6 feet
Shoulder Arms was created on 1918-10-20.
20' x 10' (200 square feet) = 22.22 square yards.
10 yards each yard has 3 feet so 10 yards is 30 feet which is greater than 20 feet
twenty . 10 - 8 = 2 2 / 10 = 20 / 100 = 20%
10 feet
from 16-20 legs
what is the volume of a square pyramid with base edges of 20 feet and a height of 10 feet
Having 20/10 vision means you can see at 20 feet what a person with normal vision can see at 10 feet. It indicates better than average vision and means you have sharper visual acuity.