Answer:
the length of rope still needed to build the swing is 180 feet.
Explanation:
To find the length of rope still needed to build the swing, we need to first convert the given lengths to the same unit of measurement.
Given:
Length of rope available = 420 feet
We know that 1 foot is equal to 12 inches. So, we can convert the length of available rope from feet to inches by multiplying it by 12:
420 feet * 12 inches/foot = 5040 inches
Now, we can subtract the length of available rope from the total length required to find the length still needed:
Length of rope still needed = Total length required - Length of available rope
Length of rope still needed = 7200 inches - 5040 inches
To convert the result back to feet, we divide by 12:
Length of rope still needed = (7200 - 5040) inches / 12 inches/foot
Length of rope still needed = 2160 inches / 12 inches/foot
Length of rope still needed = 180 feet
Therefore, the length of rope still needed to build the swing is 180 feet.