Answer:
y = 3x + 2
2 tiles
Explanation:
The line on the graph crosses the y-axis at y=2. That is the value of y when x=0.
The line has a rise of 3 squares for each 1 square it goes to the right, so its slope (the coefficient of x) is 3.
The "rule" is then ...
y = 3x + 2
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If we assume that x represents a figure number and y is a number of tiles, then for x=0, y=2 (as described above).
Figure 0 has 2 tiles.
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The pattern seems to be that each figure has 3 more tiles than the previous one.