If a-b/b=3/7,which of the following must also be true?

Correct Answer is : ab=107a/b=10/7ba=710

Correct Answer is : ab=107a/b=10/7ba=710

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SAT Mathematics Practice Test 4

Question : 6 of 58

Marks: +1, -0

\frac{a-b}{b}=\frac{3}{7}

,which of the following must also be true?

Solution:

The equation

\frac{a-b}{b}=\frac{3}{7}

can be rewritten as

\frac{a}{b}-\frac{b}{b}=\frac{3}{7}

, from which it follows that

\frac{a}{b}-1=\frac{3}{7},

\frac{a}{b}=\frac{3}{7}+1=\frac{10}{7}

.Choices A, C, and D are incorrect and may be the result of calculation errors in rewriting

\frac{a-b}{b}=\frac{3}{7}

For example, choice A may be the result of a sign error in rewriting

\frac{a-b}{b}

\frac{a}{b}+\frac{b}{b}=\frac{a}{b}+1

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