swerve wrote:Roses can be purchased individually for $4.30, one dozen for $36, or two dozen for $50. What is the greatest number of roses that can be purchased for $680?

A. 156
B. 162
C. 318
D. 324
E. 325

The OA is C.

Please, can any expert explain this PS question for me? I can't get the correct answer. I need your help. Thanks.

If we're trying to maximize the number of roses, we want to purchase as many roses as possible in bundles of two dozen, as that's the best deal.
If we're paying $50 for each bouquet of two-dozen, then the most we can spend on these bouquets is $650, as this is the largest multiple of 50 under 680. 50 goes into 650 13 times. So for $650, we can buy 13 bouquets of 24 flowers each, or 24*13 = 312 flowers.

A and B are out.

We've got $30 left to spend. Clearly we can't afford the dozen roses for $36. If we can't afford 12 more roses then the correct answer must be less than 324 (As 312 + 12 = 324.) Eliminate D and E.

We're left with C. No need to do more math.