When two straight lines intersect, one of the resulting angles is 120 degrees. Find the degrees of the remaining angles.

To solve this problem, remember that when two straight lines intersect, two pairs of adjacent angles are obtained, the sum of each is 180 °, which means that the sum of all four angles is 360 °. When we cross, we get two pairs of vertical angles. Recall that the vertical angles are equal. Therefore, since one angle is 120 degrees, then the second is equal to 120 degrees. Let’s calculate the degree measure of the other two angles.
360- (120 + 120) / 2 = 360-240 / 2 = 120/2 = 60 degrees.
Answer: 120 °, 120 °, 60 °, 60 °.