A model of the expression -3 - (0.5) with an arrow is shown on the number line in the imag below.
In Mathematics and Geometry, a number line is a type of graph that is composed of a graduated straight line, which typically comprises both negative and positive numerical values that are located at equal intervals along its length.
This ultimately implies that, every number line would primarily increase in numerical value towards the right from 0 and decrease in numerical value towards the left from 0.
Next, we would subtract the given numbers from each other as follows:
x = -3 - (0.5)
x = -3 - 0.5
x = -3.5
In conclusion, each interval on this number line represents 2 units.