Question

explain what it means for one set to be a subset of another set. How do you prove that one set is a subset of another set?

Short answer

Hence, discussed the condition that when one set is a subset of another set.

Step-by-step solution

Definition of set 

A collection of well defined and distinct objects.

Subset of a set

X Is a subset of Y if every element of X is also an element of Y.

Notation:$\mathrm{X}\subseteq \mathrm{Y}$

For example the set of the integers Z is a subset of the real numbers R. Because all integers are also real numbers

$Z\subseteq R$

To prove that X is a subset of Y, we would need to show that every element of the set X is also an element of the set Y