Question

if x varies directly as y and x = 7 when y = 28 , find x when y is 84 ?
Answer = yes ya no ​

Answer 1

Answer:

if x varies directly as y then

7:28::x:84

84*7=28x ( product of means equals the product of extremes)

x=84*7/28

x=21

Answer 2

Answer:

$\large\bold\red{x=21}$

Step-by-step explanation:

Given,

x varies directly as y.

Let,

The Equation formed be,

• x = ky

Also,

it's given that,

When x = 7, y = 28

Therefore,

We get,

$= > 7 = 28k \\ \\ = > k = \frac{7}{28} \\ \\ = > k = \frac{1}{4}$

Now,

We have to find x when y = 84,

Therefore,

We get,

$= > x = ky \\ \\ = > x = \frac{1}{4} \times 84 \\ \\ = > \bold{ x = 21}$