## Algebra 1: Common Core (15th Edition)

When you model the equation using algebra tiles, you get 3 green tiles, 5 red tiles, the black bar, 2 more green tiles, and 3 yellow tiles. The green tile represents $x$. To isolate $x$ or the green tile by itself on one side of the equation or the black bar, add the number of red tiles to the yellow tiles on the other side. Subtract the 2 green tiles on the other side of the black line from the green tiles on the other side. You do this to cancel out the $-5$, so you add $+5$ to both sides, which leaves you with $2x=8$. Two green tiles and $8$ yellow tiles. Divide 8 by 2. x is equal to 4.