Question

a man buys a plot of land at 360000 he sells one third at a loss of 20% again he sells two third of the plot at a profit of 25% at what price should he sell the remaining plot in order to get a profit of 10% on the whole

Answer 1

Solve it by parts ,,much easier way
we'll consider loss as negative and profit as positive

1/3(-20%) + 4/9(20%) + 2/9(x%) = 10%

x% = 35%

he must sell remaining at 35% profit to earn 10% profit over all.

note::There's assumption done in question that 2/3of remaining is sold at 25% profit. Otherwise question can't be solved