Calculate Mary's total earnings including commission and find the sum of June and Peter's ages given June's age is 12.

Let June's age be $j$.
Peter is twice as old as June, so Peter's age is $2j$.

The expression for the sum of their ages is $\boxed{3j}$.

Substitute $j = 12$ into the expression from part (a).

The sum of their ages is $\boxed{36 \text{ years}}$.

Since the diagram is not fully visible, I will assume a standard configuration for parallel lines intersected by a transversal, where the $70^\circ$ angle is an acute angle in the upper-left position of the top intersection.

Let the $70^\circ$ angle be $\angle X$.

• Angle A: Assume A is the angle adjacent to $\angle X$ on a straight line.

  $$A = 180^\circ - 70^\circ = 110^\circ$$

  Reason: Angles on a straight line sum to $180^\circ$.

• Angle B: Assume B is the corresponding angle to $\angle X$.

  $$B = 70^\circ$$

  Reason: Corresponding angles are equal when lines are parallel.

• Angle C: Assume C is the co-interior angle with $\angle X$.

  $$C = 180^\circ - 70^\circ = 110^\circ$$

  Reason: Co-interior angles (consecutive interior angles) sum to $180^\circ$ when lines are parallel.

The values are $\boxed{A = 110^\circ, B = 70^\circ, C = 110^\circ}$.

To plot the points A(-2,4), B(0,0), C(1,-1), and D(3,1) on the graph grid:

• Point A (-2, 4): Start at the origin (0,0). Move 2 units to the left along the x-axis, then 4 units up parallel to the y-axis. Mark this point.
• Point B (0, 0): This is the origin itself. Mark this point.
• Point C (1, -1): Start at the origin. Move 1 unit to the right along the x-axis, then 1 unit down parallel to the y-axis. Mark this point.
• Point D (3, 1): Start at the origin. Move 3 units to the right along the x-axis, then 1 unit up parallel to the y-axis. Mark this point.

After plotting all four points, use a ruler to draw straight lines connecting them in order:

1. Join point A to point B.
2. Join point B to point C.
3. Join point C to point D.

This will form a path on the graph.