Question

Which equation could you use to solve for x in the proportion StartFraction 4 over 5 EndFraction = StartFraction 9 over x EndFraction? 4 x = 14 4 x = 45 5 x = 13 5 x = 36

Answer 1

Answer:

4x=45

Step-by-step explanation:

4/5=9/x, so first you would multiply 5×9 (because cross products are always equal) and you would get 45. Since 4x has to also equal 45, the answer is 4x=45.

Hope this helps (P.S. I got it right on the test)!

Answer 2

Answer:

(b) 4 x = 4 5 is the needed expression to solve for the value of x.

Step-by-step explanation:

Here, the given proportion is simplified as:

$\frac{4}{5} = \frac{9}{x}$

Now, to simplify any proportion of the form $\frac{a}{b} = \frac{c}{d}$  the simplest way is CROSS MULTIPLICATION.

So, cross multiplying  $\frac{a}{b} = \frac{c}{d} \implies ad = bc$

Similarly cross multiplying $\frac{4}{5} = \frac{9}{x}$, we get:

4 (x)  = (9) (5)

or, 4 x  = 45

Hence, 4 x = 45 is the needed expression to solve for the value of x.