I am trying to figure out how to assign the variables and set up the equation.

Let the three angles be x,y,z.
By the Given conditon "The sum of the measures of the angles of a triangle is 180". It is clear that,
[tex]x+y+z=180^{\circ}[/tex]By the given conditon " The sum of the measures of the second and third angles is three times the measure of the first angle". It is clear that,
[tex]y+z=3x[/tex]Subsititute y+z=3x in the equation x+y+z=180,
[tex]\begin{gathered} x+y+z=180^{\circ} \\ x+3x=180^{\circ} \\ 4x=180^{\circ} \\ x=\frac{180}{4} \end{gathered}[/tex]So by furthur simplifying the value of x can be founded,
[tex]\begin{gathered} x=\frac{180}{4} \\ x=45 \end{gathered}[/tex]The value of x is 45 degree.
Subsitute the value of x in the equation y+z=3x. we get,
[tex]\begin{gathered} y+z=3x \\ y+z=3\times45 \\ y+z=135 \end{gathered}[/tex]By the given condition "The third angle is 29 more than the second". It is clear that,
[tex]z=29+y[/tex]Subsititute the equation z=29+y in the equation y+z=135,
[tex]\begin{gathered} y+z=135 \\ y+29+y=135 \\ 2y+29=135 \\ 2y=135-29 \\ 2y=106^{\circ} \\ y=53^{\circ} \end{gathered}[/tex]The value of y is 53 degree.
Subsitute the value of x and y in the equation x+y+z=180. We get,
[tex]\begin{gathered} x+y+z=180^{\circ} \\ 45+53+z=180 \\ 98+z=180 \\ z=180-98 \\ z=82^{\circ} \end{gathered}[/tex]The value of z is 82 degree.
So the value of x is 45 degree, the value of y is 53 degree and the value of z is 82 degree. That is,
[tex]x=45^{\circ},y=53^{\circ},z=82^{\circ}[/tex]