If the elevator can hold up to 2,100 pounds, that means 2,100 is the maximum. So we have an inequality, not an equation because the elevator can also hold less than 2,100 pounds. Our inequality would represent "less than or equal to".
To write this out, we start with a variable, let's say "w" for "weight".
w
Then, we add our inequality symbol "less than or equal to".
w

Last, we insert our weight limit which is 2,100 pounds.
w
2,100
That represents the inequality for his specific problem. To graph this on a number line, we simply use the symbol that matches "less than or equal to", which is a closed circle. And since we are talking about the weight being LESS THAN, our arrow is going to the left. Attached is an image of how to graph this on a number line.