The value is decreased by 10%. This means that current price is 100%-10%=90% of the original price. Now we can solve this by using ratios
90% $11000
100% $x
Now we cross multiply numbers and solve it for x:
90*x = 100 * 11000
90x = 1 100 000
x= 1 100 000 / 90
x= $12 222,22
When Maggie bought a car theprice was $12 222,22