let x = second angle
let x + 10 = first angle
let 2( (x) + (x+10) ) = third angle.
Since the interior of a triangle equals 180° then,






Inputting the value of x gives us each angle.
second angle = 25°
first angle = x + 10 = 25 + 10 = 35°
third angle = 2( (x) + (x+10) ) = 2( (25) + (25+10) )
= 110°