Consider this option:
1. if ∠1=x; ∠2=x+10 and ∠3=2x-6. then using the sum of the angles of a triangle ∠1+∠2+∠3=180°;
2. using the rule ∠1+∠2+∠3=180, it is possible to re-write as x+x+10+2x-6=180 or 4x+4=180; ⇔ x+1=45; ⇒ x=44.
3. if x=44°, then ∠1=44°; ∠2=x+10=54°; ∠3=2x-6=82°, the give triangle is acute triangle.
answer: acute triangle.
