What are some signs of physical change

if you are talking about the body then increased hormones as physical changes  with growing in sexual parts  and for guys increase in with muscles and growing in breast.

If it was of a change in physical properties. as of natural in universe then it would be melting, transition to different states of matter.

Explanation:

When everyone gets of age they grow and mature and these kind of changes happen

The reason for that would be of the change of strength, change of durability, changes to crystal form, textural change, shape, size, color, volume and density, These are some examples of physicals changes

the old price per ounce is c/4.

the new price per ounce is c/3.6.

the ratio of the old price to the new one is

(c/4)/(c/3.6) = (c/c)×(3.6/4) = 0.9 . . = 9/10 . . "nine tenths" in either form