Question

if y varies directly with x and y is 12 when x is 9 what is x when y is 4

Answer 1

Answer:

X is 3 when Y is 4.

Answer 2

So, the required value  $x$ is 3.

Proportional:

Properly related in size, degree, or other measurable characteristics; corresponding: Punishment ought to be proportional to the crime. 3. Mathematics Having the same or a constant ratio.

The first part is  y varies directly with x then,

$y \propto x\\y=kx$... (1) where k is proportional constant

Now, substituting $y=12, x=9$ in equation (1) we get,

$12=9k\\k=\frac{4}{3}$

Substituting $k=\frac{4}{3}$ in equation (1) with $y=4$ then,

$4=(\frac{4}{3})x\\ x=3$

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