If he bought the land for $300,000, to make a profit of 10% it means the profit will be
= 10% * $300,000
= $30,000
If he sold one-third at a loss of 20% then the selling price will be
= 1/3 * $300,000 * (100% - 20%)
= $80,000
If he sells two-fifths at a gain of 25% then the selling price would be
= 2/5 * $300,000 * (100% + 25%)
= $150,000
To make an overall profit of 10%, he must sell the remaining for
= $300,000 + $30,000 - $80,000 - $150,000
= $100,000
