Find the angles of triangle ABC if angle A is 30 degrees greater than angle C and angle B is 40 degrees.

From the condition, we know that angle A is 30 ° greater than angle C, and angle B is 40 °. In order to find all the angles of the triangle ABC, compose and solve a linear equation with one variable.

We denote the angle C using the variable x, then the angle A is x + 30.

We also need a theorem on the sum of the angles of a triangle, which says that the sum of the angles of a triangle is 180 °.

Let’s compose and solve a linear equation:

x + x + 30 + 40 = 180;

2x = 180 – 70;

2x = 110;

x = 55 ° angle C, then angle A is 55 + 30 = 85 °.