if we see the equation.. 23x+21y = 130;

then, the boundary conditions are .. 6>x> 0, 6>y>0

Also, x and y are positive integers which means x &Y cannot have fractional values.

So, its not a hit and trial..but can be calculated in few iterations.

ritula wrote:

but in B, there are 2 variables and only one eq?dnt we require 2 eqs 2 find 2 variables? The way found the sol is hit and trial. Im very confused.Can u pls explain?

GMAT TIGER wrote:

23x+21y = 130

1. If 23 cents pencil is 1, then 21 cents pencil should be 7.

2. If 23 cents pencil are 2, then 21 cents pencil should be 4.

3. If 23 cents pencil are 3, then 21 cents pencil should be 1.

4. so on.........

which makes the total value 130 cents? 2?

23x2 + 21x4 = 46 + 84 = 130

B.