innocous wrote:

A pencil costs $3 and a pen costs $7. If pens and pencils have to be bought independently and in lots

which are multiples of 5. Are the number of pens bought equal to the number of pencils bought.

1)Total money spend was $100.

2)Total money spend was $ 200.

Let the no of pencils bought = 5x and no of pens = 5y

The question asks

is x=y?From F.S 1, we know that

3*5x+7*5y = 100or 3x+7y = 20. The only solution for this equation with positive integrals values for (x,y) is

x=y=2. Sufficient.

From F.S. 2, we know that

3x+7y = 40. Now,

y=1,x=11 satisfies this equation. Also,

y=4,x=4 satisfies the equations. Insufficient.

A.

Though not a good question for GMAT.

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All that is equal and not-Deep Dive In-equality

Hit and Trial for Integral Solutions