let y =21 and x =1.5. If y varies directly with x, fins y when x =9

Question

myininaya · Answer

y varies directly with x
how do you write this as an equation?

myininaya · Answer

hint: On your previous post it said how to

anonymous · Answer

I don't understand it..

anonymous · Answer

can you give me a written example

myininaya · Answer

Well on your previous post is said 
that y varies directly as x meant y=kx
where k is a constant

myininaya · Answer

So we have the equation y=kx

myininaya · Answer

Now you are also given an order pair on this line x=1.5,y=21
enter these values in the equation and solve for k

anonymous · Answer

Direct variation is $\dfrac{x}{y}=C$ for some constant $C$.  The first two value give you enough information to find $C$, and then use your new formula to solve the problem.

myininaya · Answer

What did you get for k?