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

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Answer 1 · 2017-03-29T22:22:25

#r=22#

The method of cross product or cross multplication is applied.

#1/3=(r-8)/(r+20#

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

Using the distributive property;

#r+20=3r-24#

Group like terms

#20+24=3r-r#

Simplify

#44=2r#

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

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

#r=22#