Answer:
1st angle = X
2nd angle = X + 7
3rd angle = X + 18
Then (sum. them): 3X + 25 = 180 ==> X = 51.67 degree
Therefore,
1st angle = 51.67 degree
2nd angle = 58.67 degree
3rd angle = 69.67 degree
Let [tex]x[/tex] be the first angle.
"The second angle of the triangle is 4 degrees more than the first angle" means that the second angle is [tex]x+4[/tex]
"The third angle is 8 degrees more than two times the first angle" means that the third angle is [tex]2x+8[/tex]
So, on the one hand, the sum of the angles of the triangle is
[tex]x+(x+4)+(2x+8) = 4x+12[/tex]
On the other hand, the sum of the sides of any triangle is 180 degrees. So, we have
[tex]4x+12=180 \iff 4x = 168 \iff x = 42[/tex]
