Question

if the three angles of a triangle are (x+15°),(6x/5)and(2x+30°/3),prove that the triangle is an equilateral triangle

Answer 1

You know the sum of the interior angles of a triangle is 180.
Add the given angles, set that sum equal to 180. Then solve for x.
Once you have x, use that to see what he value of each angle is (use the three terms in the problem). If they are all the same, hen the triangle is equilateral.
You can do this one