L'hopital's rule problem

i don't how my text book gets - 1

explain and showing work would

Calculate the density of benzene if 300ml of it weighs 263g. a. 0.88 g/ml b. 1.14 g/ml c. 78,900 g/ml d. 37 g/ml

How many real-number solutions does the equation have? -4x^2 + 10x + 6 = 0 a. no solutions b. two solutions c. infinitely many solutions d. one solution

Which steps could be part of the process in algebraically solving the system of equations, y+5x=x^2+10 and y=4x-10