SOLUTION: A retailer marks up all products by 75 percent. If the selling price of a set of plastic bowls is $4.00 what was the cost to the retailer?

Since it's easier, I think students should learn that when 
something is raised 75%, that means that the new price is 
175% of the old price.  So I'll approach it that way.

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175% of x is $4.00.

1.75x = 4.00
    x = 4.00/1.75
    x = $2.285714286

$2.28 if he raised it a tiny bit more than 75%.
$2.29 if he raised it a tiny bit less than 75%.

(He could not theoretically have raised it EXACTLY 75% because he cannot
charge a fraction of a penny).

Edwin