If y varies directly as x, find the direct variation equation for the situation

y=3 when x=21

y = x / 7

Step-by-step explanation:

For us to get direct variation equation, we must introduce a constant term.

If y varies directly as x:

y ~ x

y = Kx

Where K, is the introduced constant.

Now let's solve to get a direct variation equation.

When y=3, x=21

We substitute, y=3 and x=21 in the

y = Kx

3 = K 21

Divide both sides by 21

3 / 21 = K 21 / 21

K = 3/21

K = 1 / 7

Therefore, we introduce K = 1 / 7 into the mother equation.

y = 1/7 * x

y = x / 7

The direct variation equation for the situation:

y = x / 7