Is a > b ?

(1) a/b = 7/10

(2) a = 70/100*b

both statements essentially say the same thing.. ratio: a:b=7:10 => 10a=7b;

now just plug in some values to see if you can get any definitive answers:

assume a=7, b=10 or a=14, b=20 and so on.... (a< b)

but there are negative answers as well.... a=-7, b=-10 => a > b

I would go with E.....

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Is a > b ?

(1) a/b = 7/10

(2) a = 70/100*b
==> transforming the original condition and the question using variable approach method, we have 2 variables (a,b) and in order to match the number of variables and equations we need 2 equations. Since there is 1 each in 1) and 2), C is likely the answer.

Using both 1) & 2) together, the answer is yes if a=-7, b=10, while the answer is no if a=7, b=10. Since the conditions and not suffiicent. the answer is E
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Is \(a>b \quad?\)

(1) \(\frac{a}{b} = \frac{7}{10}\)

Taking \(a = 7\) and \(b = 10,\quad \frac{a}{b}=\frac{7}{10}\)

Is \(a>b ? : No\) ; as \(7<10\).

Taking \(a = - 7\) and \(b = -10,\quad \frac{a}{b} = \frac{-7}{-10}=\frac{7}{10}\)

Is \(a>b ? : Yes\) ; as \(-7>-10\).

Statement \(1\) alone is not sufficient.

(2) \(a = \frac{70}{100}*b\)

\(a = \frac{70}{100}*b\) can be reduced to \(a = \frac{7}{10} *b\)

Taking \(a = 7\) and \(b = 10,\quad a=\frac{7}{10}*b\)

Is \(a>b ? : No\) ; as \(7<10\).

Taking \(a = - 7\) and \(b = -10,\quad a = \frac{7}{10}b\)

Is \(a>b ? : Yes\) ; as \(-7>-10\)

Statement \(2\) alone is not sufficient.

As Statement (1) and statement (2) are the same with only exception that in statement 1, b cannot be zero while statement 2, b can be 0.
Combining both will also be insufficient to answer: Is a > b ?