If $${\log _{10}}7 = a,$$then $${\log _{10}}\left( {\frac{1}{{70}}} \right)$$is equal to

If $${\log _{10}}7 = a,$$then $${\log _{10}}\left( {\frac{1}{{70}}} \r

1.	If $${\log _{10}}7 = a,$$then $${\log _{10}}\left( {\frac{1}{{70}}} \right)$$is equal to
A.	(1 + a)
B.	1 + a)-1
C.	$\frac{a}{10}$$
D.	$\frac{1}{10a}$$
Answer» B. 1 + a)-1