Answer:
y = m x + b equation for a straight line
if x = o then y = 4 from graph
y = 0 + 4 and b = 4
If x = 8 then y = 24 from graph
24 = m * 8 + 4 substituting in our equation
m = 20 / 8 = 2.5 giving slope or rate of change
y = 2.5 x + 4 the final equation with a slope of 2.5
As a check using the graph:
We see that if y = 24 then x = 8
24 = m * 8 + 4 substituting in our equation
m = 20/8 = 2.5 agreeing with the value found
