Hello,
Since we're given that both of these angles are acute(less than 90 degrees), we can form these 2 inequalities:[tex]10x+3\ \textless \ 90[/tex] and [tex]3x+9\ \textless \ 90[/tex]. Isolating x in both inequalities we get: [tex]x\ \textless \ 6.7[/tex] and [tex]x\ \textless \ 27[/tex]. Therefore we have [tex]6.7\ \textgreater \ x\ \textless \ 27[/tex]. Now let's form another inequality byadding the 2 original inequalities: [tex]10x+3+3x+9\ \textless \ 180[/tex]. Simplifying we get [tex]13x+12\ \textless \ 180[/tex]. Solving for x we get [tex]x\ \textless \ 14[/tex]. So now we have [tex]6.7\ \textgreater \ x\ \textless \ 14[/tex].Therefore, x must be positive and for any positive x in this range 10x+3 is greater than 3x+9. Let me know if that doesn't make sense!