If you know the answer to these plz answer.

Step-by-step explanation:  

You can readily see from the diagram, above, that the side length of the middle cube will be between 3 and 4.  You want to determine to the nearest hundredth what value between 3 and 4 represents the side length of the cube whose volume is 45 units^3.

Please note:  the middle cube has been mislabeled.  Instead of volume = 30 units^3, the volume should be 45 units^3.

Here's the procedure:

Guess an appropriate s value.  Let's try s = side length = 3.5

Cube this:  (3.5 units)^3 = 42.875.  Too small.  Choose a larger possible side length, such as 3.7:  3.7^3 = 50.653.  Too large.

Try s = 3.6:  3.6^3 = 46.66.  Too large.

Choose a smaller s, one between 3.5 and 3.6:  3.55^3 = 44.73.  This is the best estimate yet for s.  Continue this work just a little further.  Try s = 3.57.  Cube it.  How close is the result to 45 cubic units?

cross multiplying, we get :

⇒ (3) × (5) = (9) × (x)

⇒ 15 = 9x