Question 1091802

If {{{x}}} and {{{y}}} vary {{{directly}}}, we have

{{{y=kx}}} 

and  if {{{x=10}}} when {{{y=3}}},we can use it to find {{{k}}} 

{{{3=k*10}}} 

{{{k=3/10}}} 

{{{k=0.3}}} 

so, equation is:{{{y=0.3x}}}

the the value of {{{x}}} when {{{y=9}}} is:

{{{9=0.3x}}}

{{{9/0.3=x}}}

{{{x=30}}}