Hello! The business problem is calculating certain Task time's of workers. I have only their total time per day and the amount task's they did in that time those task are split into types (Its that 18 variable's I already mentioned). An example: 8x+4y+0z+...+5n=4300[seconds] 8x+0y+0z+....+0n=1000[seconds] Yes some workers have only 1 task done and other don't but that's not a problem as I can zero-fill those spot's or easily ignore unsolvable equations. I'm trying to solve 2000 equations (2000workers/day) with 15 variables (15 diffrent tasks) . I found an algorithm that solves an equation (Gauss elimination) so that part I have behind now I'm puzzled how to calculate all combination's of those equations. I need to match each equation with all solvable combination's of others. I want have a all the possible variable values as output then I can run some statistical program to find my sweet spot for the task time but that's another story. Any nice c++ trick you could suggest ?