y = x + intercept

y = x + c     OR      y = x + b

Slider - you can change the intercept on the y-axis

y = x

y = 2x

y = x + 1

y = 2x + 1

y = gradient × x
y = mx
y = ax

y = x + intercept
y = x + c
y = x + b

y = gradient × x + intercept
y = mx + c
y = mx + b
y = ax + b