Name     quantity     price
A        1            10.0
A        3            26.0
B        1            15.0
B        3            30.0
...

Name     quantity     price
A        1            10.0
A        2            extrapolate([1, 3], [10.0, 26.0], 2)
A        3            26.0
B        1            15.0
B        2            extrapolate([1, 3], [15.0, 30.0], 2)
B        3            30.0
...