What are the differences when using addition or subtraction to simplify an answer compared to multiplication?

Question

can you show me an example

Answer 1

Normally, you'd use both. In fact, one of the biggest tools is the distributive property of multiplication over addition, where you pull out common factors.

Examples:

3x + 6x = (3+6)x = 9x -- a simplification.

2x + 4y = 2(x+2y) -- that's not a simplification itself, but it may be a step in simplifying a fraction.