To identify the constant of proportionality from the given points, we first observe the coordinates of the plotted points. The format of the points is \( (x, y) \):
- \( (0, 0) \)
- \( (2, 14) \)
- \( (4, 28) \)
- \( (6, 42) \)
- \( (8, 56) \)
- \( (10, 70) \)
- \( (12, 84) \)
The constant of proportionality (k) is found by dividing \( y \) by \( x \) for any nonzero point:
For \( (2, 14) \): \[ k = \frac{y}{x} = \frac{14}{2} = 7 \]
For \( (4, 28) \): \[ k = \frac{28}{4} = 7 \]
For \( (6, 42) \): \[ k = \frac{42}{6} = 7 \]
For \( (8, 56) \): \[ k = \frac{56}{8} = 7 \]
For \( (10, 70) \): \[ k = \frac{70}{10} = 7 \]
For \( (12, 84) \): \[ k = \frac{84}{12} = 7 \]
In all cases, the constant of proportionality \( k \) is \( 7 \).
Therefore, the constant of proportionality for the graph is \( \boxed{7} \).