Question

If y varies directly with x, and when y is 24, x is 6, what is y when x is 9?

Answer 1

"varies directly with" lets you set up the equation
y = k*x
For some constant k. It's not a great equation because we don't know k yet, but it's something.

"When y is 24, x is 6" lets us plug in one pair of y and x to get
23 = k*6
Which lets us find k. Once we've found k, our y =k*x equation becomes a lot better.