Answer:
Profit = $20
Explanation:
It is given that a man bought a horse for $60 and sold it for $70. Then he bought it back for $80 and sold it for $90.
Total revenue = $70 + $90 = $160
Total expenditure = $60 + $80 = $140
The formula for profit is
[tex]Profit = Revenue - Expenditure[/tex]
Substitute $160 for revenue and $140 for expenditure in the above formula.
[tex]Profit = 160-140[/tex]
[tex]Profit = $20[/tex]
Therefore, he make $20 in the horse trading business.