If x and y vary directly, and x = 12 when y = 3, what will be the value of x when y = 9? 36 27 4.5

100

The value of x when y = 9 is 36

Solution:

Given that, x and y vary directly,  

And x = 12 when y = 3,  

We have to find what will be the value of x when y = 9

Now from the given information,

x = cy ---- eqn 1

where "c" is the proportionality constant

Now, substitute x = 12 and y = 3 in (1)

12 = c(4)  

c = 3

Then, (1) ⇒ x = 4y

So, when y = 9 ⇒ x = 4(9) ⇒ x = 36

Hence, x value is 36 when y value is 9, so 1st option is correct

which expression can be used to convert 80 us dollars (usd) to australian dollars (aud)?

1 usd = 1.0343 aud

1 aud = 0.9668 usd

step-by-step explanation:

sorry just need the points