Not including tax, a total of 19 pens and markers cost $11.50. The pens cost $0.25 each, and the markers cost $0.75 each. Which system of equations could be used to solve for the number of pens (p) and the number of markers (m) bought?

A.) { p + m = 30.5
{ 0.25p = 0.75m

B.) { p + m = 19
{ 0.25p + 0.75m = 11.5

C.) { p + m = 11.5
{ 0.25p + 0.75m = 19

D.) { 19( p + m ) = 1.00
{ 0.25p + 0.75 = 11.5