solving 2-step equations

Where do you see equation here? It's just simple operation of division 12/-16 can be reduced to -(3/4)

As said, this isn't an equation. Equation states that two values are respective to each other, this is a calculation.

12 / -16 = - 12/16
-- In multiplication and division operations, the "polarity" of the result depends on the amount of minus-signs in the calculation
-- If the amount of minus-signs is even (2,4,6,8) then the result is positive, uneven amount results in negative result.

- 12/16 can further be processed to a "nicer" result by dividing the fractions sides by 4
-> - 12/16 is as much as - 3/4, the outcome is the same

In math you usually want the result as simple as possible, so this is the right answer.