imc

For this problem, we will have to write a three-variable equation, but not necessarily solve it. Let $a,b,$ and $c$ represent the original portions of Al, Betty, and Clare, respectively. At the end of one year, they each have $a-100,2b,$ and $2c$. From this, we can write two equations, marked by (1) and (2). $$a+b+c=1000$$ $$(1).2a+2b+2c=2000$$ $$a-100+2b+2c=1500$$ $$(2).a+2b+2c=1600$$ (Equations (1) and (2) are derived from each equation above them.) Since all we need to find is $a,$ subtract the second equation from the first equation to get $a=400.$ Al's original portion was $\boxed{\text{textdollar}400}$.