okays,i need to start get my brain working .

let's do some maths together...

[(1989 - 2011) x -2] ÷ 11 = x

x to the power 2 = y

{[20000 -(y-3x)(y-x)] ÷ 8} - 50 = z

z = the number of days back to perth

for a great tan and all the summer goodies :D