What sets of numbers are included in the real numbers

The standard deviation for a set of data is 5.5. the mean is 265. what is the margin of error?

Jeremy wants to determine the number of solutions for the equation below without actually solving the equation. which method should jeremy use?

Given: transversal t passed through parrallel lines r and s.prove: < 3 = < 6 < 4 = < 8what is the next step in the proof? choose the most logicsl approach