Which equation could you use to solve for x in the proportion 4/5=9/x

Show me how you find x and determine what x is you i appreciate it : )

Asap describe the transformations required to obtain the graph of the function f(x) from the graph of the function g(x). f(x)=-5.8sin x. g(x)=sin x. a: vertical stretch by a factor of 5.8, reflection across y-axis. b: vertical stretch by a factor of 5.8,reflection across x-axis. c: horizontal stretch by a factor of 5.8, reflection across x-axis. d: horizontal stretch by a factor of 5.8 reflection across y-axis.

You have 12 balloons to blow up for your birthday party. you blow up 1/3, and your friend blows up 5 of them. what fraction of the baloons still need blowing up