(a) Find the greatest common factor (GCF) of 30 and 18 . GCF \( =\square \) (b) Use the GCF to factor \( 30-18 \). \( 30-18=\square \times(\square-\square) \)

To find the greatest common factor (GCF) of 30 and 18, we break each number down into its prime factors. The prime factors of 30 are 2, 3, and 5 (since \( 30 = 2 \times 3 \times 5 \)), while the prime factors of 18 are 2 and 3 (since \( 18 = 2 \times 3^2 \)). The common prime factors are 2 and 3, so the GCF is \( 2 \times 3 = 6 \). Now, let's use the GCF to factor \( 30 - 18 \). First, we calculate \( 30 - 18 = 12 \). Using the GCF of 6, we can write \( 12 \) as \( 6 \times (2) \) or \( 6 \times (4 - 2) \). Thus, the complete expression is \( 30 - 18 = 6 \times (5 - 3) \).