The angles of the triangle would be represented by x for the congruent sides and 10x for the 3rd angle. All of the angles in a triangle equal 180° The equation would be set up like this: 12x=180 x=15° 10x= 150°
TO simplify the answer make common denominator which would be 12 so 5/6 times 2 on each 10/12 & 3/4 x3 becomes 9/12 so those make 1 7/12 add with 1 and 7