yes linear, x int is when his net profit is 0, y int is the net profit when he has 0 clients

x int (90, 0) represents when the pool is empty, y int (720, 0) represents how much water before the draining starts, no line symmetry

x int of f(x) is farther to the right than g(x), y int of f(x) is higher than the y int of g(x), the slope of f(x) is greater than the slope of g(x)