1. Solve system by substitution method. x+y=6
2. Utilize synthetic division to divide f(x)=x^3+15x^2+71x+105 by x+7. Utilize result to determine all zeroes of "f"
3. Use Descartes rule of signs to find possible number of positive and negative real zeros for given function. f(x)=6x8-9x7+x6-3x+18