Answer:
6
Step-by-step explanation:
Write the prime factorizations:
24 = 2³ × 3
30 = 2 × 3 × 5
The greatest common factor is the product of the common factors at their lowest exponents.
GCF = 2 × 3
GCF = 6
The first option .
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If I understand your question correctly then it's simple all you have to do is use the numbers in the place of the b and c so the question would be what is 8-7 which equals 1