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Hi Brian, WE all use the term percent in a nonprecise way and this question really makes that clear. You accountant has yet another valid way o interpret your question. He (or she) sees the cost to the customer, $\$C$ in three distinct parts. 20% of $\$C$ is the administration cost, 15% of $\$C$ is your profit and the remainder is your direct cost. The remainder after removing the 20% plus 15% is 65% and thus your fixed cost is 65$ of $\$C.$ That is \[0.65 \times \$C = \$100.\] Dividing both sides of this equation by $0.65$ gives \[\$C = \frac{\$100}{0.65} = \$153.85\] All three answers are correct. Which you choose depends on what your interpretation of percentage of what. Penny  


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