Question 653489
 
{{{RS=8y+4}}}, {{{ST=4y+8}}}, {{{RT=15y-9}}}

if we take that

{{{RS+ST = RT}}}...=>... {{{(8y+4)+(4y+8)=15y-9}}}


{{{8y+4+4y+8=15y-9}}}...solve for {{{y}}}

{{{12y+12=15y-9}}}

{{{9+12=15y-12y}}}

{{{21=3y}}}


{{{21/3=y}}}

{{{highlight(7=y)}}}

now find:

{{{RS=8y+4}}}
{{{RS=8*7+4}}}
{{{highlight(RS=60)}}}


{{{ST=4y+8}}}
{{{ST=4*7+8}}}
{{{ST=28+8}}}
{{{highlight(ST=36)}}}

{{{RT=15y-9}}}
{{{RT=15*7-9}}}
{{{RT=105-9}}}
{{{highlight(RT=96)}}}

check:

{{{RS+ST = RT}}}

{{{60+36 = 96}}}

{{{96 = 96}}}