Find the value of x. Then classify the triangle by its angle measures.

One angle of the triangle is$x°$, Second angle is given as$2x°$, and third angle is given as$\left(3x-18\right)°$.

Sum of all angles of a triangle is$180°$.

The sum of all the angles of a triangle is$180°$.

This gives us-

$\begin{array}{c}\left(3x-18\right)°+2x°+x°=180°\\ 3x°-18°+2x°+x°=180°\end{array}$

Add all the x.

$6x{}^{\circ }-18{}^{\circ }=180°$

Add 18 on both the sides.

$6x{}^{\circ }-18{}^{\circ }+18{}^{\circ }=180{}^{\circ }+18°$

This gives us,

$6x{}^{\circ }=198°$

Now, divide both sides by 6.

$\frac{6x°}{6}=\frac{198°}{6}$

This will give us the value of x.

$x=33°$

The first angle of the triangle is given as $x°$and the value of first angle is$x=33°$.

Second angle of the triangle is given as$2x°$. To find the value of the angle, multiply 2 with 33.

$2\times 33{}^{\circ }=66°$

So, the second angle is$66°$.

Since, the third angle of the triangle is given as$\left(3x-18\right)°$.

To find the value of the angle, multiply 3 with 33 and then subtract 18 from it.

$3\times 33{}^{\circ }-18{}^{\circ }=81°$

So, the third angle is$81°$.

The value of xis$x=33°$.

One angle is$33°$, second angle is $66°$and the third angle is$81°$.

All the three angles of the triangle are different. Hence, it is a scalene triangle.