Its simply helps you visualizing what part is negative/positive. For inequations (ex: 3x+9>10), its super important to let you know from where to where the equation is, in my example, higher than 10.
I wpuld say B...because that can be the one Delta planet
2×5^{2} if you don't understand its 2 times 5 to the second power.
2/6 * 24 = 8 council members vote for a new park
so they need to convince 13-8 = 5 more members