In triangle ABC, the angle A is 3 times the angle B, and the angle C is 20 degrees. Determine the angles A and B.

Given a triangle ABC.

Angle C = 20 °;

Let x be angle B, then angle A = 3 * x.

Let’s find what angle A and angle B are equal to.

Let’s make an equation.

x + 3 * x + 20 = 180;

4 * x + 20 = 180;

We transfer the known values to one side, and the unknown values to the opposite side. When transferring values, their signs are changed to the opposite sign. That is, we get:

4 * x = 180 – 20;

4 * x = 160;

x = 160/4;

x = 40;

This means that the angle B = 40 °, and the angle A = 3 * 40 ° = 120 °.