Answer:
Step-by-step explanation:
If you draw in BD, you can show that triangle BCD = triangle BAD by SSS
That means that <A = <C parts of congruent parts are congruent.
<A + <C + 115 + 71 = 360
<A + <C + 186 = 360 All convex quadrilaterals have 4 interior angles that add to 360 degrees
<A + <C = 360 - 186
<A + <C = 174
So call <A and < C = x
x + x = 174
2x = 174
x = 174 / 2
x = 87
<A = 87
