Hi there,

For (ii), one method we can use to find the equation of BC is to put an arbitrary value for its y-intercept. Since we know the coordinates of B, and B lies on BC, the equation
y = -(1/2)x + c should apply for the point B as well. Thus, you can find the value for C by substituting the coordinates of x and y into
y = -(1/2)x + c

For (iii), you can think of AD as BC with each value of x on BC being increased by 3. Thus, to get the new y-intercept for the equation of AD, just add it onto the y-intercept of BC with (3 * the positive gradient of AD)

For (iv), the concepts used will be very similar to that in (ii) and (iii).

Good luck, and comment if you have any questions.