13. 4/5
14.11/25
15.-1 7/20
16. 4/5
17. -1 5/10
18.4 9/20
simplifying
we get 
Step-by-step explanation:
We need to simplify: 
Solving:
Applying the rule:
log a + log b = log(ab)

So, simplifying
we get 
Keywords: Simplifying Logarithms
Learn more about Simplifying Logarithms at:
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Okay, so to find like denominators you need to find a number that both denominators go into. For 15, they both go into 45. 9 goes in 5 times and 15 goes in 3 times. So multiply their numerators by 5 and 3. It would be 25/45 for 5/9 and it would be 12/45 for 4/15. Do the same for 16 and 17, for 16 they both go into 42 and for 17 they both go into 42.
Fourty million, twenty-three thousand, thirty-two.
40,000,000 + 20,000 + 3,000 + 30 + 2