Question

Variables y and x have a proportional relationship, where y = 18 when x = 2.

What is the value of x when y = 36?

Answer 1

`\huge\boxed{\sf x = 4}`

Explanation:

Given that:

`y \propto x`

Converting proportionality into equality

`y = kx` ----------------(1)

y = 18 when x = 2

Put it in Eq. (1)

`\displaystyle 18 = k(2)\\\\Divide \ both \ sides \ by\ 2\\\\(18)/(2) = k\\\\9 = k\\\\ \boxed{k = 9}`

Now,

x = ? when y = 36

Put it in Eq. (1)

`36 = (9) x\\\\Divide \ both \ sides \ by \ 9\\\\36 / 9 = x\\\\4 =x \\\\\boxed{x = 4}\\\\\rule[225]{225}{2}`