Anne has a sample of a substance. its volume is 20 cm3, and its mass is 100 grams. what is the sample’s density?

The answer is:  " 5 g / cm³ " .

Explanation:  

Density = mass divided by volume ; or: "D = m / V " ;

    and is expressed as:  "mass per unit volume" ;

The mass, "m", is expressed in units of "g" (grams) ; and
the volume, "V" is expressed in units of "cm³ " or "mL" ; ("cm³ ", in this case);

{Note the exact conversion:  " 1 cm³ = 1 mL " .} .

So, if:  the mass, "m = 100 g"  {given} ; 

and the volume,  " V = 20 cm³ " {given} ;

Plug these values into the formula/equation to solve for the density, "D" ;

    D =  m / V =  (100 g) / (20 cm³)  
 
         = (100 ÷ 20)  g / cm³  = 5 g /cm³ .

    The answer is:  " 5 g / cm³ " .

Amethod of procedure that has characterized natural science since the 17th century, consisting in systematic observation, measurement, and experiment, and the formulation, testing, and modification of hypotheses.