The logarithm written as a sum of logarithm and simplified as much as possible is 
<h3>Simplifying Logarithms</h3>
From the question, we are to write the given logarithm expression as a sum or difference of logarithms
The given logarithm is

This can be written as

From one of the rules of logarithm, we have that

Thus,
becomes

This can be further simplified into


If desired, this can be further simplified into




Hence, the logarithm written as a sum of logarithm and simplified as much as possible is 
Learn more on Simplifying logarithms here: brainly.com/question/17851187
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rob can dig 1/10ft in one hour
Shayna can dig 1/7ft in one our
together they can dig
1/10+1/7
(7+10)/70 in one hour
17/70
in for hours they can dig
17/70×4
68/70
the left work is 2/70
in 60 minutes they can dig 17/70
1/70 work can be done in 60 minutes/17
2/70 work can be done in 60/17×2 minutes
7.088 minutes
for the entire work they take 4hours and 7 minutes
80 Because the numbers are going up by 10
I think C is the correct awnser