The answer is

In the choices; the coefficients 21, 32 and 10 are not perfect squares.
Answer:
f
Step-by-step explanation:
6 mm
Set up a proportion of 12/9=8/x. Cross multiply and this gives us 12x=72. Now divide both sides by 12 and you get 6.
Answer:
One milliampere is equal to 0.001 ampere.
Step-by-step explanation:
Mili, refers to thousandth. (for example, millimeter or milliliter.)
3/5x-5
I believe this is the expression that is described.