Answer:
x=37
Step-by-step explanation:
Lets remember that in a triangle, the sum of all internal angles is equal to 180
this means the following
(x+13) + (2y) + (3y-20)=180
x+5y-7=180
Next, lets identify the supplementary angle, these meet the following condition. (3x+9)+2y =180
The system is given by these equations:
x+5y=187
3x+2y=171
if we isolate 'y' variable from second equation we have y= 1/2 * (171 - 3x), lets use that in the first.
x+5* 1/2 * (171 - 3x)=187
From this we obtain x=37
