Attached you will see the solution using the trig plane and general solutions.
(5.75,0)
Let A be (x1,y1) , B be (x2,y2) , P be (x,y) and the ratio be m:n
Formula is,
x=(x2*m+x1*n)/(m+n)
y=(y2*m+y1*n)/(m+n)
Its max is 780
2/3 + 1/6 = 5/6
650/5=130
650+130=780
This is substitution, it's very simple once you get the hang of it!
okay, what you want to do is plug in the numbers you already have, to get the number you don't have(r).
First, you plug in the numbers.
1. P= $2000
A=$2543
t= 4(years)
r=?
2543=2000^r(4)
Secondly, you want to solve the equation.