Question

suppose y varies directly as x. if x=7 when y=21, find x when y=30

Answer 1

Answer:

x = 10

Step-by-step explanation:

Direct variation:

 In direct variation, if one variable increase or decrease, the other variable also increases or decrease in the same way.

 $\sf \dfrac{x}{y}=k\\\\\\x = ky$

When x = 7 & y = 21, k will be,

       $\sf k = \dfrac{x}{y}\\\\\\ = \dfrac{7}{21}\\\\k = \dfrac{1}{3}$

Now, we have to find the value of x, when y = 30

         $\sf x = 30*\dfrac{1}{3}\\\\\\x = 10$