PLz help me solving this

Asilkworm 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 aa single thread with a typical length of 300 yards. choose a reasonable number of silk fibers in a thread write an equation to find the total length of the silk fibersused in 300 yards of the thread

Find the zeros of each function. f(x) = 6x^2 - 7x - 20

Which of the following vectors are orthogonal to (2,1)? check all that apply