You could estimate by doing 600x3=1800
(becasuse of the 0's in 600 it is easier to do 6*3=18 and then add two 0's to the end 1800)
then you simply multiple 640x3=1920
Answer:

Step-by-step explanation:
we know that
To make one hair ties is needed 3 3/8 inches of elastic
so
using proportion
Find out how many hair ties can you make with 9 feet of elastic
Remember that

Convert 9 ft to inches

Convert mixed number to an improper fraction

using proportion

the answer is graph b on edg.
580/2=290
the airplane flies 290 per half hour.