Question 172262
Let's see the Right Triangle:
{{{drawing(400,400,-1,6,-1,8,triangle(0,7,5,0,0,0),locate(.2,5.5,2x+10),locate(3,1,3x+20),line(0,0,0,.5),line(0,.5,.5,.5),line(.5,.5,.5,0),red(locate(.3,5,34^o)),red(locate(3.5,.8,56^o)))}}}
We know the sum of the angles is 180deg:
So, {{{2x+10+3x+20+90^o=180^o}}}
{{{5x+120=180}}}
{{{5x=180-120=60}}}
{{{cross(5)x/cross(5)=cross(60)12/cross(5)}}}
{{{x=12^o}}}
So, {{{2*12+10=24+10=highlight(34^o)}}}
And, {{{3*12+20=36+20=highlight(56^o)}}}
check: 
{{{90+34+56=180}}}
{{{180^o=180^o}}}
Thank you,
Jojo