7.D.1 — Combine like terms with negatives.
Step 01 of 03
Like terms have the SAME variable to the SAME power. Combine by adding their coefficients (with sign).
Step 02 of 03
Watch the sign immediately to the LEFT of each term. That sign belongs to the coefficient.
Step 03 of 03
Different powers don't combine: and stay separate.
Key insight
Same variable + same power = combinable. Coefficient inherits the sign immediately to its left. Different powers never combine, no matter how similar they look.