This may be long, but please help! Will mark Brainliest!

A silkworm winds its cocoon out of one long silk fiber. To make silk thread, 3 to 10 of these silk fibers are unwound from their cocoons and combined into a single thread with a typical length of 300 yards.

a. Explain why you cannot write an equation to find the exact total length of the silk fibers used in a 300-yard silk thread.

b. Choose a reasonable number of silk fibers in a thread. Write an equation to find the total length of silk fibers used in 300 yards if the thread.