I believe it would be (-2,-2) i may be wrong though i dont have my graphing papers
One value: would be a single valued function, or just one answer.
Real numbers would be: natural numbers, whole numbers, integers, rational numbers (fractions and repeating or terminating decimals), and irrational numbers.
No solution: there is no answer to the question.
Your simplified answer is 10 (ten)
X + x + 30 = 510
2x = 480
x = 240
there were 240 women and 270 men.