Question 985335
<pre>
The exterior angles of any polygon have sum 360°.

3 of them are 15°, 25° and 70° and the other (n-3) exterior angles are 
50° each.

Sum of exterior angles = 15°+25°+70°+(n-3)*50° = 360°
                                110°+(n-3)*50° = 360°
                                     (n-3)*50° = 250°
                                    {{{((n-3)*"50°")/"50°"}}}{{{""=""}}}{{{"250°"/"50°"}}}
                                           n-3 = 5
                                             n = 8  


So the polygon has 8 sides.

Edwin</pre>