$$(5,1)$$ - 

$$x + y = 6 $$

$$(-2,4)$$ - 

$$ y = x + 6 $$

$$(8,2)$$ - 

$$x - y = 6$$

$$(1,6)$$ - 

$$2x + y = 8$$

$$(2,3)$$ - 

$$x + 2y = 8 $$

$$(1,3)$$ - 

$$ 2x + 2y = 8 $$

$$6(x + 4)$$ - 

$$6x + 24$$

$$6(2x + 4)$$ - 

$$12x + 24$$

$$4(2x + 1)$$ - 

$$8x + 4$$

$$4(x + 1)$$ - 

$$4x + 4$$

$$2(3x + 2)$$ - 

$$6x + 4$$

$$6(2x - 4)$$ - 

$$12x - 24$$

constant - 

a term that does not vary

coefficient - 

a numerical multiplier of a specific variable in a term

gradient - 

a measure of how steep a line is

$$y$$-intercept - 

the coordinate where a line crosses the $$y$$ axis

origin - 

the coordinate $$(0,0)$$

equation of a straight line - 

a relationship which, when plotted, forms a straight line

A (purple) - 

gradient $$1\over 2$$, $$y$$-intercept $$(0,-2)$$

B (green) - 

gradient $$1\over 2$$, $$y$$-intercept $$(0,2)$$

C (pink) - 

gradient $$-2$$, $$y$$-intercept $$(0,-2)$$

D (blue) - 

gradient $$-{1\over 2}$$, $$y$$-intercept $$(0,2)$$

E (black) - 

gradient $$2$$, $$y$$-intercept $$(0,-2)$$

$$y = 5x - 4$$ - 

gradient $$5$$, $$y$$-intercept $$(0,-4)$$

$$y = 4 - 5x$$ - 

gradient $$-5$$, $$y$$-intercept $$(0,4)$$

$$y = -4x - 5 $$ - 

gradient $$-4$$, $$y$$-intercept $$(0,-5)$$

$$ y = 4x + 5 $$ - 

gradient $$4$$, $$y$$-intercept $$(0,5)$$

$$y = 5x + 4$$ - 

gradient $$5$$, $$y$$-intercept $$(0,4)$$

$$y = 5 - 4x $$ - 

gradient $$-4$$, $$y$$-intercept $$(0,5)$$