Can someone help this

Step-by-step explanation:

The common factor is the largest number that goes into both of those numbers evenly. We do this by finding the prime factorization of each:

25: 5,5

35: 5,7

The common number to both is 5, so 5 is the common factor of both the numerator and denominator.

the mistake in the pattern is that :

b. the decimal point was moved one too many place values each time

the correct pattern could be made by :

b. moving the decimal point to the right the same numbers of place values as the exponents

it is a. 4.2 because 7.6-3.4 gets the remaining length of 4.2. i might be wrong but i am pretty sure this is the answer.