Math tell whether the ordered pair is a solution of the equation?
The idea is to replace one variable in the equation by the first number in the ordered pair, the other variable with the second number in the ordered pair, do the calculations, and see whether the resulting expressions are indeed equal.
It means that you can validate the solution by verifying the answer. The answer of 19 for the equation of 47 - 28 = n, is reasonable because 28 + 19 = 47. If the equation is more difficult, showing your work every step along the way to the answer. Just show your work in detail and then checking your solution makes the answer of the math equation reasonable.