How do you solve $\frac{1}{3} = \frac{r - 8}{r + 20}$ $\frac { 1} { 3} = \frac { r - 8} { r + 20}$ ?

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Answer 1 · 2017-03-29T22:22:25

$r = 22$ $r=22$

The method of cross product or cross multplication is applied.

$\frac{1}{3} = \frac{r - 8}{r + 20}$ $1/3=(r-8)/(r+20$

$1 (r + 20) = 3 (r - 8)$ $1(r+20)=3(r-8)$

Using the distributive property;

$r + 20 = 3 r - 24$ $r+20=3r-24$

Group like terms

$20 + 24 = 3 r - r$ $20+24=3r-r$

Simplify

$44 = 2 r$ $44=2r$

Divide both sides by $2$ $2$ so that $r$ $r$ stands alone

$(cancel(2)r)/cancel2=44/2$

$r=22$

How do you solve \frac { 1} { 3} = \frac { r - 8} { r + 20}13=r−8r+20\frac { 1} { 3} = \frac { r - 8} { r + 20}?