Bunuel wrote:

emmak wrote:

A retailer orders u units of an item for which he pays d dollars. However, he mistakenly receives u - 3 items. How much was he overcharged, in terms of d and u?

A. 3d - u

B. 3du - 9

C. (3d)/u

D. (u−d)/3

E. (du)/3

Say the retailer ordered u = 4 items for d = 4$ (1$ per item). Thus:

He received 4 - 3 = 1 unit for 4$, which is 3$ more than the item actually costs.

Now, plug u = 4 and d = 4 into the answer choices to see which one yields 3. Only C fits: (3d)/u = (3*4)/4 = 3.

Answer: C.

Hope it's clear.

Please help me understand where am i going wrong ..

Amount per items actually recieved = d/u-3

Amount per items to be recieved = d/u

Overcharged amount = d/u-3 - d/u = 3d/u(u-3)