From statement I alone, 4 markers can be purchased for $36. Therefore, cost of one marker = $9.
Greatest number of markers that can be purchased for $18 = 2
Statement I alone is sufficient. Answer options B, C and E can be eliminated.
From statement II alone, if the cost of each marker is increased by $3, 5 less markers can be purchased for $180.
If the cost of one marker is $x, number of markers = \(\frac{180 }{ x}\).
If the cost of one marker is $(x+3), number of markers = \(\frac{180 }{ (x+3)}\)
The number of markers in the second case is 5 less than the number of markers in the first case.
Therefore, (\(\frac{180}{x}\)) – 5 = (\(\frac{180}{x+3}\)).
We have one equation in x, therefore, a definite value of x can be calculated. Since we can find a unique value for x, we can also find a unique value for the greatest number of markers that can be purchased for $18.
Statement II alone is sufficient. Answer option A can be eliminated.
The correct answer option is D.
Hope that helps!
Aravind B T