Problem
Find $x \in \mathbb{R}^4$ such that $$(4, -3, 1, 7) + 2x = (5, 9, -6, 8)$$
Solution
First isolate $2x$ by subtracting the leftmost vector from both sides of the equation which can be done by applying D1.12, D1.16 and D1.17: $$2x = (5, 9, -6, 8) - (4, -3, 1, 7) = (1, 12, -7, 1)$$ Then divide by $2$ on both sides of the equation: $$x = \left(1/2, 6, -7/2, 1/2\right)$$ This is the solution.