Help me please i don't know this

The angle of a triangle are given as 6x,(x-3), and (3x+7). find x then find the measures of the angles

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.

A.s.a.! this is a similarity in right triangles. next (solve for x)a.) 12b.) 5c.) 12.5d.) [tex] 6\sqrt{3} [/tex]