The measures of the three angles of a triangle form an arithmetic sequence. What must be the measure, in degrees, of at least one of its angles?

Let the three angles be a1, a1 + d and a1 + 2d

So....we have that

a1 + (a1 + d) + (a1 + 2d) = 180°

3a1 + 3d = 180° divide through by 3

(a1 + d) = 60°

So......one of the angles must be 60°

Thank you so much!