Tony bought some stock for $504. If each share had cost $4 less he could have bought 3 more shares for the same $504. How many shares of stock did he buy

1 answer

L*Price=504
(L+3)*(Price-4)=504

LP-4L+3P-12-504=0
next L=504/P
504-4*504/P+3P-516=0
now combine terms, and multiply by P

-12P-2016 +3P^2=0

divide by 3, rearrange terms...
P^2-4P-672=0

(P-26)(P-22)=0
So the at the higher price (26), he bought L=504/26