Find the angles of a triangle if one of them is 50 degrees larger than the other and 20 degrees less than the third angle.

The sum of all the angles of a triangle is 180 °. Since the angle А is 50 ° more than the angle ∠В, and 20 ° less than the angle ∠С, then we express:
x – angle ∠A;
x – 50 – angle ∠В;
x + 20 – angle ∠С;
x + x – 50 + x + 20 = 180;
x + x + x = 180 + 50 – 20;
3x = 210;
x = 210/3 = 70;
∠А = 70 °;
∠В = 70 – 50 = 20 °;
∠С = 70 + 20 = 90 °.
Answer: ∠А = 70 °; ∠В = 20 °; ∠С = 90 °.