Calculate the valor of B, thx!

3.4a=57.8 what is the the value of a

Aquadrilateral has exactly 3 congruent sides davis claims that the figure must be a rectangle why is his claim incorrect.

Aline is perpendicular to another line m2= (-1/m1), where m1 is the slope of the original line and m2 is the slope of the perpendicular line. which of the following equations represents the line that passes through the point (-2,1) and is perpendicular to the line below?