To determine which line is the steepest and which two lines are parallel, we can calculate the slopes of each line using the formula for the slope \( m \) between two points \((x_1, y_1)\) and \((x_2, y_2)\):
\[ m = \frac{y_2 - y_1}{x_2 - x_1} \]
Let's calculate the slopes for each line:
Line A:
Points: \( (3, 9) \) and \( (0, 0) \)
\[ m_A = \frac{9 - 0}{3 - 0} = \frac{9}{3} = 3 \]
Line B:
Points: \( (8, 15) \) and \( (1, 1) \)
\[ m_B = \frac{15 - 1}{8 - 1} = \frac{14}{7} = 2 \]
Line C:
Points: \( (12, 21) \) and \( (3, 3) \)
\[ m_C = \frac{21 - 3}{12 - 3} = \frac{18}{9} = 2 \]
Line D:
Points: \( (9, 14) \) and \( (1, 2) \)
\[ m_D = \frac{14 - 2}{9 - 1} = \frac{12}{8} = 1.5 \]
Now we have the slopes:
- \( m_A = 3 \)
- \( m_B = 2 \)
- \( m_C = 2 \)
- \( m_D = 1.5 \)
Conclusion:
- The steepest line is Line A with a slope of 3.
- The two lines that are parallel are Line B and Line C, as they both have a slope of 2.