Question 669293

{{{RT = 25}}}........given

{{{RS = x + 8}}}, and {{{ST = 3x + 5}}}.........given

given also that {{{S}}} is a point {{{on}}}{{{ RT}}} which means {{{RT=RS +ST}}}

now substitute given values for {{{RT = 25}}},{{{RS = x + 8}}}, and {{{ST = 3x + 

5}}} in {{{RT=RS +ST}}} and you have {{{25=(x + 8) +(3x + 5)}}}