fupapack wrote:

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how is this not $36?

They want a 20% markup at retail. If retail price were $36, the markup ($6) would only be 16.7% of $36 (6/36 = 0.1666...)

To calculate retail price, you divide the purchase price by (1-markup).

Proof:

Let x be the retail price. The markup is 20% of x, or 0.2*x

x = 30 + 0.2*x

x - 0.2*x = 30

You factorize:

(1 - 0.2)x = 30

x = 30/(1 - 0.2)

x = 37.5

Does it make sense?