(a) find the gcf of 42 and 35

Gcf = ?

(b) use the gcf to factor 42-35
42-35=?x(?+?)

(a) To find the greatest common factor (GCF) of 42 and 35, we'll look for the largest number that divides both numbers.

Factors of 42: 1, 2, 3, 6, 7, 14, 21, 42
Factors of 35: 1, 5, 7, 35

The largest number that appears in both lists is 7, so the GCF of 42 and 35 is 7.

GCF = 7

(b) Now, using the GCF to factor the expression 42 - 35, we express both numbers as multiples of their GCF and then factor out the common factor.

42 = 7 * 6
35 = 7 * 5

42 - 35 = 7 * 6 - 7 * 5

Factoring out the common factor of 7, we get:

7 * (6 - 5)

Since (6 - 5) is equal to 1, the expression simplifies to:

7 * 1 or simply 7

So, 42 - 35 is equal to 7, and when factored using the GCF, it is 7 * (6 - 5) or just 7.