Subtract 8x-4y from the sum of 8x+10 and -16x+18y

There are 12 boy and13 girls in a class. if the teacher randomly chooses a student’s name out of a hat what is the probability it will be a girl

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.

Abari owns 100 shares of stock a and 45 shares of stock b. for the past month, his stocks have been fluctuating inversely. stock a decreased by m cents per share and stock b increased by n cents per share. which equation can be used to find the total change in value of jabari's shares per month?