The Reverse Gear

Expanding turns $4\left(x+5\right)$ into $4x+20$. Factoring goes back. A term is one part of a sum, like $6x$ or 18. To factor:

• Find a number that divides every term.
• Write it in front of a bracket.
• Inside the bracket, write each term divided by that number.

$$6x+18 = 6\left(x+3\right)$$

Check by expanding: $6\cdot x+6\cdot 3$ gives back $6x+18$.