Final answer:
Two inequalities that Tim can use to compare a positive number, a, and a negative number, b, are |a| > |b| and a > 0 and b < 0.
Step-by-step explanation:
To compare two numbers, a and b, where a is positive and b is negative, we can use two inequalities:
The magnitude of a must be greater than the magnitude of b. This can be represented as |a| > |b|.
The value of a must be greater than 0 and the value of b must be less than 0. This can be represented as a > 0 and b < 0.
These inequalities help Tim compare the positive and negative numbers a and b based on their magnitudes and values.