Interpreting Function Notation, Graphs, and Context

The pollution level at $100$ days is $13$ ppm more than the pollution level at $2$ days.

The pollution level after $100$ days of Nicholas collecting data is $13$ ppm.

The pollution level after $2$ days of Nicholas collecting data is $13$ ppm.

The pollution level after $100$ days of Nicholas collecting data is $13$ ppm less than the pollution level after $2$ days.