Flash Graphs

I am having a serious problem, well its a serious problem for me cause i suck at maths

I am trying to draw a graph in flash

lets say its has 50 points i need to plot

The highest point is 24078.4, the lowest point is 23846.9

my graph is 320px high so 24078.4 must be at 320px, 23846.9 must be at 0px

how do i work out where the numbers between that must be plotted?
for example


if someone could work this out and show me a formula i really would appreciate it so much