Question

find the value of a - 1 by a if a + 1 by a equal to 17 by 4

Answer 1

$\frac{a + 1}{a} = \frac{17}{4} \\ 4a + 4 = 17a \\ 4 = 13a \\ so \: a \: = \frac{4}{13}$
$a - 1 = \frac{4}{13} - 1 \\ = \frac{ -9 }{13} \div a \\ = \frac{ - 9}{13} \div \frac{4}{13} \\ = \frac{ - 9}{4}$