What are the uses of ` X ' and ` Y ' in maths ?
What is the number of solutions to the equation -LSB- math -RSB- 3x +7 y = 2011 -LSB- / math -RSB- for which both -LSB- math -RSB- x -LSB- / math -RSB- and -LSB- math -RSB- y -LSB- / math -RSB- are positive integers ?