user: I need the greatest common divisors for my math assignment, specifically for these pairs: 45 and 60, 81 and 27, 144 and 96, and 100 and 80. Can you provide the GCDs for all these pairs?

Available functions:
name: math_gcd
description: Calculates the greatest common divisor of two numbers.
parameters: type: dict
properties: a: type: integer
description: The first number. This should be the larger number.
b: type: integer
description: The second number.
required: a
b