Step-by-step explanation:
[tex]see \: if \: 10 \: are \: left \: then \: we \: hve \: spent \\ 250 - 10 = 240 \: dollars \\ [/tex]
hence
[tex]six \: flasks \: cost \: 240 \: dollars \\ so \: if \: we \: divide \: 240 \: by \: 6 \: we \: get \: 40 \: \\ [/tex]
so one flask costs 40$