Question

If y varies directly with x. x is 30 y is 10 what is x when y is 9?

Answer 1

y varies directly with x is written as \(\large y=cx\). c is a constant .
Now did you mean "x is 30 when y =10?

Answer 2

The problem just says x is 30 when y is 1...

Answer 3

Ok.

Answer 4

So \(10=30c\) we solve for constant c to create another relationship when y =9.
c= 1/3.
So now when y= 9, we substitute c back into our original formula \(\large \color{red} {y=cx}\) but this time we have y = 9,c=1/3.
9=1/3 x where x = 9(3) = 27.

Answer 5

Thank you so much!

Answer 6

no problem :)