Question 260860
Since it's a triangle the angles sum to 180.
{{{2x+3x+20+5x-10=180}}}
{{{10x+10=180}}}
{{{10x=170}}}
{{{x=17}}}
{{{2x=34}}}, acute angle, less than 90. 
{{{3x+20=51+20=71}}}, acute angle, less than 90. 
{{{5x-10=85-10=75}}}, acute angle, less than 90.