Now come to addition and subtraction of rational expressions. Following are the general formulas.
(a/c) + (b/c) = (a + b)/c (a/c) -( b/c) = a - b /c
As these have illustrated we've got to remember that to add or subtract rational expression or fractions we have to have common denominators. If we don't have common denominators then we have to first get common denominators.