Answer:
Step-by-step explanation:
x  - the smallest angle
3x  - the middle angle
2x  - twice the smallest angle
3·3x  -  3 times the middle angle
twice the measure of the largest angle (the difference of 3 times the middle angle and twice the smallest angle):  3·3x - 2x = 7x
7x÷2 = 3.5x  - the largest angle
The sum of angles in any triangle is 180°, so:
x + 3x + 3.5x = 180°
7.5x = 180°      {divide both sides by 7.5}
x = 24°
small angle:  x = 24°
middle angle:  3x = 3·24° = 72°
large angle:   3.5·24° = 84°