one would have to believe since there is only 3 angles, it is a triangle which has a total of 180 degrees. They give us the degrees for all the angles, we just have to add them up and solve for x.
180° = ∠A + ∠B + ∠C 180° = 65° + (3X-10)° + 2X° Drop the parentheses 180° = 65 + 3x - 10 + 2x Combine like terms 180° = 55 + 5x subtract 55 from both sides 125° = 5x divide both sides by 5 25° = x substitute this value for x into the ∠'s
The sum of the interior angles in any triangle is 180 So m<A + m<B + m<C = 180 65 + 3x - 10 + 2x = 180 5x + 55 = 180 5x = 180 -55 5x = 125 x = 125/5 x = 25