What number, when added to the numerator and to the denominator of $\frac{5}{8}$ $5/8$ , results in a fraction whose value is 0.4?

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Answer 1 · 2018-04-28T22:00:20

$n = - 3$ $n=-3$

let $n$ $n$ be that number

$\frac{5 + n}{8 + n} = 0.4$ $(5+n)/(8+n)=0.4$

Many ways to solve, I prefer turning it into a fraction:

$\frac{5 + n}{8 + n} = \frac{2}{5}$ $(5+n)/(8+n)=2/5$

$2 (8 + n) = 5 (5 + n)$ $2(8+n)=5(5+n)$

$16 + 2 n = 25 + 5 n$ $16+2n= 25+5n$

$- 9 = 3 n$ $-9=3n$

$n = - 3$ $n=-3$

Another way:
$\frac{5 + n}{8 + n} = 0.4$ $(5+n)/(8+n)=0.4$

$5 + n = 0.4 (8 + n)$ $5+n=0.4(8+n)$

$5 + n = 3.2 + 0.4 n$ $5+n= 3.2+0.4n$

$1.8 = - 0.6 n$ $1.8= -0.6n$

$n = - 3$ $n=-3$

What number, when added to the numerator and to the denominator of 5/8585/8, results in a fraction whose value is 0.4?