Answer
$x=11$
Work Step by Step
When you model the equation using algebra tiles, you get 1 green tile, 4 red tiles, the black bar, and 7 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. You do this to cancel out the -4, so you add +4 to both sides, which leaves you with x=11. One green tile and 11 yellow tiles.
