=> A = s^2

=> 25 = s^2

=> 5 = s or s = 5

Since you wanted one side, so u square rooted both sides and got s = 5, which is the length of one side of the square.

So you’re done with 1/3 of the question. Now u gotta figure out the volume. Also Note that each side of a cube is of same length, which in this case is 5. And the volume formula is length x width x height. When we put it as a formula, we write it as:

V = L (length) x W (width) x H (height)

V = 5 x 5 x 5

V = 125 unit^3 (since u didnt provide the unit e.g cm, m, in etc)

You’re done with 2/3rd of the question now!

Last but not least, you figure out the mass. And in order to find the mass, you need to have the density formula, which is:

Density = Mass x Volume

You know the density (19.3) and the volume (125). Now you have only one unknown. You plug these numbers into the density equation as:

=> D = M x V

=> 19.3 = Mass x 125

=> 19.3/125 = Mass

=> Mass = 0.154 (whatever the unit is)

So, DONE!

Tip: Just work slowly through the problem and think what should come up first in order to find the missing numbers.

Cheers!