With regard to mathematics, what is in excepted statement of fact that is used to prove other statements

Ac contractor is building a new subdivision outside of the city. he has started work on the first street and is planning on the other streets to run in a direction parallel to the first. the second street will pass through (-2,4) find the equation of the location of the second street in standard form. a.2x+y=2 b. x-y=2 c.2x+y=2 d.x+y=2

[10 points, algebra 2-simplifying complex fractions]according to my answer key the restrictions are -1 and 4. but why not positive 1?

Twelve less than a number is at most 20