Answer:
"18", "54", and "108"
Explanation:
Angles:
A straight line has an angle of 180 degrees. It can be seen as "half a circle", which has an angle of... 360 degrees, and since it's half, it's just 180 degrees.
Now we're also given the angles that compose the straight line (x, 3x, and 6x), and by adding these angles together, we should get the angle of the straight line. So that means that:

Now from here we can just combine them all into one term:

Now divide both sides by 10:

Our angles are equal to "x", "3x", "6x", and to calculate their value, we just plug in "18" as x giving us: "18", "3(18)", "6(18)" which simplifies to the angles: "18", "54", "108"