Cancel factors, not terms
Factor the numerator and denominator before cancelling common factors. A denominator may never be zero.
(x² − 4)/(x + 2) = x − 2, with x ≠ −2.
Find a common denominator
When adding fractions, rewrite each one using the same denominator, then add the numerators.
1/x + 1/(x + 1) = (2x + 1)/(x(x + 1)), with x ≠ 0 and x ≠ −1.
Multiply and divide
Multiply numerators together and denominators together. To divide, multiply by the reciprocal of the second fraction; that fraction must be nonzero.
(2x/3) × (9/(4x)) = 3/2, with x ≠ 0.