Hey!
Simi bought study table = $ 9000
It means S.P = $9000
Profit = 20%
We know,
S.P = \frac{100+profit%}{100} \times C.P\\ S.P = \frac{100+20}{100} \times 9000\\ S.P = \frac{120}{100} \times 9000 \\ S.P = 10800
Now,
Profit = S.P - C.P
= 10800-9000
= $ 1800