Question 338600
First he bought the cycle for $21.  So that is -$21.
Then he sold it for $35 but received a check for $75 and gave the difference back.
So $75 - $35 = $40 returned to the customer.
Now the check had bounced so he did not actually gain any money.

So in all he lost: $21 + $40 = $61
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Alright since you had a question, lets give these people names.

Bob bought a cycle for $21.
(Bob -$21)
Then Bob sold the cycle to Jim for $35.  Jim gave Bob a check for $75.
$75 - $35 = $40
Bob takes the check from Jim and then Bob gives Jim $40.
(Bobs money: -$21 + -$40 + $70 Check)
Now when Bob goes to the bank to cash the check, it bounces. That means that Bob does not get any of the $70 from the check.
(Bobs money: -$21 - $40)
That measns that Bob has lost $61 today.
But Jim has gaind $40 plus a cycle.