Question

1. 63a - 42b

Explanation:

Step1: Find GCD of 63 and 42

The factors of 63 are \(1, 3, 7, 9, 21, 63\), and factors of 42 are \(1, 2, 3, 6, 7, 14, 21, 42\). The GCD is 21.

Step2: Factor out GCD

Factor out 21 from \(63a - 42b\): \(21(3a - 2b)\)

Answer:

\(21(3a - 2b)\)