Which of the following will result in a rational number? Select all that apply. A. 645+9√4
B. 645−5√7
C. 645×9√4
D. 645÷5√7
help me please

What are the measures of ∠a, ∠b, ∠c and ∠d? explain how to find each of the angle measure.

Abby is preparing fruit punch for her party. she starts with a bowl filled with liquid that has 1/2 fruit juice and 1/2 sprite, but she decides it's too fruity. so she pours out 1/4 of the liquid, and then fills the bowl up again with sprite. what fraction of the punch is now sprite?

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.