1 share sold at 96$ - profit of 20%
so 120/100*x = 96 => x= 80 so profit of 16 (write as +16)

2nd share sold at 96$ - loss of 20%
so 80/100*x = 96 => x=120 so loss of 24 (write as -24)

so over all profit/loss = +16-24 = -8
so loss of 8$

I hope it's clear

well there is a standard shortcut formula for such type of problems.

if two items are sold at a selling price of Rs.x each. One at a profit of p% & another at a loss of p% then there is a total loss which in percentage terms is given by (p^2)/100% & the total loss is given by
2.(p^2).x/(100^2 - p^2).



Thanks!