Like terms

Like terms have exactly the same letters and powers: 3a and −5a, or 2x² and x². Add their numbers; the letters stay the same.

  1. 5a + 3b − 2a + b
  2. a terms: 5a − 2a = 3a
  3. b terms: 3b + b = 4b
  4. = 3a + 4b

The sign belongs to the term after it. x² and x are not like terms, and neither are 3x and 3.

Multiplying and dividing

Multiply the numbers, then the letters: 3a × 4b = 12ab, and 2x × 5x = 10x².

Divide the numbers, then cancel letters: 12x³y ÷ 4x = 3x²y.

To subtract a whole bracket, change every sign inside it: (7x + 2) − (3x − 5) = 7x + 2 − 3x + 5 = 4x + 7.