First of all, In an angle bisector, it is a line passing through the vertex of the angle that cuts it into two equal smaller angles.
The formula for the distance between two points is

Note that, if two points have one coordinate in common, this formula simplifies to

(the first if they share the y coordinate, the second if they share the x coordinate).
So, these are the lengths of the sides:

(because they share the y coordinate)

(standard formula)

(because they share the y coordinate)

3 hours and 30 minutes can be rewritten as 3.5 hours
If the bird is flying constantly for 3.5 hours at 40 miles per hour:
3.5 x 40 = 140 miles
Use PEMDAS. Start by eliminating the exponents. you should be left with 3 numbers on bottom and 3 on top
multiply them then divide