📐 Part 1: Finding Equations from Graphs

Instructions: To find the equation of a line from a graph:

1. Find the y-intercept (where the line crosses the y-axis)

2. Calculate the gradient (rise ÷ run)

3. Write in the form y = mx + c

The y-intercept is: __________

The gradient is: __________

The equation is: y = __________ x + __________

📊 Part 2: Finding Equations from Two Points

Method: When given two points (x₁, y₁) and (x₂, y₂):

1. Calculate gradient: m = (y₂ - y₁) ÷ (x₂ - x₁)

2. Substitute into y = mx + c using one point to find c

Step 1: Gradient = __________ = __________

Step 2: Using point (2, 8): 8 = __________ × 2 + c

Step 3: c = __________

Final equation: y = __________ x + __________

🎯 Part 3: Extension & Application

a) Write an equation where y = total cost and x = number of text messages:

b) What would 100 text messages cost in total? $__________

Hint: Parallel lines have the same gradient.

Write an equation for the amount of water (y) after x hours: y = __________

How much water remains after 8 hours? __________ litres