Pls help
8th grade math

What are the soultion(s) to the quadratic equation 40- x^2=0

Ellen makes and sells bookmarks. she graphs the number of bookmarks sold compared to the total money earned. why is the rate of change for the function graphed to the left?

According to the general equation for conditional probability if p(anb)=3/7 and p(b)=7/8 what is p(a i b)