900-573=327 To reach their goal the least amount of books they need to read is 327
X-2y = 3
-2y=3-x move the x over to the other side
-y=3/2 -1/2x divide both sides by 2
y=1/2x - 3/2 divide both sides by -1
Distance of A from cliff = 1500·arctan(30°) ≅ 723.5 ft
distance of B from cliff = 723.5+1000√3 ≅ 2455.6 ft
tanθ = 2455.6/1500 = 1.637
θ = arctan(1.637) ≅ 58.6°
angle of depression = 90-θ ≅ 30°