Question 933366
At the beginning of the day, both stocks have a price of 10 in some currency.
(If there is no currency that will do that, I can invent one).
At the end of the day, the price of stock A is
{{{10+(1/10)*10=10+1=11}}} ,
while the rice of stock B is
{{{10-(1/10)*10=10-1=9}}} ,
so the new price of stock A, as a fraction of the new price of stock B, is
{{{highlight(11/9=1&2/9)}}}
 
NOTE:
Solved as shown above, you can easily get to the answer,
which is a great advantage for timed tests where you do not need to "show your work".
If you need to show your work, and/or
if your teacher objects to the use of made-up currencies,
you can do the same calculations starting with
"Let {{{x}}} be the price of either stock at the beginning of the day."
Then, the new price of stock A at the end of the day is
{{{x+(1/10)*x=x+0.1x=1.1x}}} ,
and the new price of stock B at the end of the day is
{{{x-(1/10)*x=x-0.1x=0.9x}}} ,
so the new price of stock A, as a fraction of the new price of stock B, is
{{{1.1x/"0.9 x"=1.1/0.9=highlight(11/9=1&2/9)}}}