20 points !! Please help me

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.

Idon’t understand! use slope intercept form to solve: through: (2,5) slope= undefined

Roy has 4 1/2 pizzas for the soccer team to split after the game. if each member is going to get 1/2 of a pizza, how many players are on the soccer team