Will give brainl. iest pls help

Which of the fallowing best completes the sequence 5,10,15, a) 30 b) 22 c)25 d)35

F(x) = (x^2 + 3x − 4) and g (x) = (x+4) find f/g and state the domain.

On a string instrument, the length of a string varies inversely as the frequency of its vibrations. an 11-inch string has a frequency of 400 cylces per second. find the frequency of a 10-icnch string.