In an isosceles triangle, the third angle is ten times the measure of each of the congruent angles. what is the measure, in degrees, of the largest angle? explain how you got this answer.

The angles of the triangle would be represented by x for the congruent sides and 10x for the 3rd angle. 
All of the angles in a triangle equal 180°
The equation would be set up like this:
12x=180
x=15°
10x= 150°

The answer is 3. parallelogram