13x + 19y <=2400
It is not a diaphantine equation.
No one said that the answers had to be integers.
https://www.desmos.com/calculator/d3u4rv8fz3
Well. This is called a linear Diophantine equation. It could have several solution! One of them is x=18 and y=114. Another would be x=37 and y=101. Another would be x=56 and y=88. Yet another could be that x=y=75!!!!!!......etc.
