If Mrs. Hill takes out a mortgage for $80,000 with a 4% interest rate, what will her interest be after 20 years? Help ASAP

Can you me with this question? i'll reward *30 points i just need with this one question so that i could solve the others. * edit: i originally set up the question to reward 30 points, but for some reason i can only reward 15. if you don't get 30, then i'm sorry. i'm still kind of new to this site

The product of 3 and a number increased by 8 is 31

Find the area of the surface obtained by rotating the curve z=4e^2y from y = 0 to y =1 about the y-axis. the area is square units