I think it represents where something is starting from, like something growing up (a chart with rising numbers)
-3x + 4y = 12
x - y = 1....x = y + 1
-3(y + 1) + 4y = 12
-3y - 3 + 4y = 12
-3y + 4y = 12 + 3
y = 15
x - y = 1
x - 15 = 1
x = 1 + 15
x = 16
one solution (16,15)
≈5.61
