Question

help/??

Answer 1

do you know how many is the sum of angles of a triangle ?

Answer 2

180 degrees

and a line how many degrees have ?

Answer 3

140 @jhonyy9 is it 40?

Answer 4

or 60

Answer 5

Since
PQ=RQ
Then the triangle is isosceles.
Thus the angles of the triangle at the bottom are congruent

Note that
Angle R + 140 = 180 (straight line)
Angle R = 40

We know that
Angle P = Angle R
Therefore we now can find angle a

40 + 40 + a = 180 (sum of triangle)
a = 100