Question

a man buys aplot at rs. 360000 he sells one third of the plot at aloss of 20%. again he sell twk third of the plot left at profit of 25% at what price as hould he sell the remaning plot in ordr to get a profit of 10 % on the whole

Answer 1

Total CP=Rs.360000
To get a profit of 10% on whole 
SP=CP+CP*Profit%/100=360000+360000*10/100
or SP=360000+36000=396000............(1)
If total land is Z then he sold  Z/3 at a loss of 20%
CP for Z/3 land=360000/3=120000
SP for Z/3 land=CP-CP*loss%/100=120000-120000*20/100
or SP for Z/3 land=120000-24000=96000..........(2)
Plot left=Z-Z/3=2Z/3
Two third of the plot left=2Z/3*2/3=4Z/9
He sold 4Z/9 land at a profit of 25%
CP of 4Z/9 land =4*360000/9=160000
SP of 4Z/9 land=160000+160000*25/100
or SP of 4Z/9 land=160000+40000=200000................(3)
Now to make 10% profit on whole
SP of Remaining plot=Total SP-SP for Z/3 land-SP of 4Z/9 land
or SP Remaining plot=396000-96000-200000=Rs.100000