Question 107259
The first angle of a triangle is 15 degrees more than the second triangle. The third angle of a triangle is three times the second angle. Use x to represent the unknown Value

let the second angle be x
the first angle is then x+15
the third angle is 3 times the second so it is 3x

all these add to 180 degrees (angle sum of triangle)
x+(x+15)+3x=180
5x+15=180
minus 15 from both sides of the equals sign
5x+15-15=180-15
5x=165

divide both sides by 5
x=165/5
x=33
so the second angle is 33
the first is 33+15=48
the third is 3 times 33=99