Math problem, Geometry.. Need a helping hand with this.. Will give brainliest

1. preform the indicated operation. then estimate to see whether the proposed result is reasonable. 811.1 - 8.039 803.071 803.061 803.161 831.061 2. the ordered pair (1, 2) lies in which quadrant? quadrant ii quadrant iv quadrant iii quadrant i 3. sean tries to drink 3 liters of water every day how my millimeters of water does he drink in a day? 0.3 ml 0.003 ml 3,000 ml 30 ml 4. find the least common multiple. (lcm). 10, 36 5 180 20 360

Which statement justifies why angle ebc measures 90?

Parabolas y=−2x^2 and y=2x^2+k intersect at points a and b that are in the third and the fourth quadrants respectively. find k if length of the segment ab is 5.