Evaluate:
Σ10, 8(27-1) =

The equation x2 – 1x – 90 = 0 has solutions {a, b}. what is a + b?

Adrawer contains 12 identical white socks, 18 identical black socks and 14 identical brown socks. what is the least number of socks you must choose, without looking, to be certain that you have chosen two socks of the same colour?

What are the solutions of the system? solve by graphing. y = -x^2 -6x - 7 y = 2