y varies directly to x. If y = 9 and x = 24, find x for y = 25.

Question

The measurement, y, varies directly with regard to another value, x. If y = 9 and x = 24, find x for y = 25.

Answer 1

y varies directly to x then y = kx

The given numbers form a ratio expressed as y/x = 9/24

To find x when y = 25

We set up another ratio is 25/x.

By the definition both ratio are equal 9/24 = 25/x

3/8 = 25/x

Divide to each side by 25

(3/8)/25 = 25/25x

3/200 = 1/x

Cross multiplication.

3x = 200

Divide to each side by 3.

3x/3 = 200/3

x = 66.66