A wastewater$/$sludge sample of $20$ mL is kept in a hot air oven at $105\backslash$deg C$,$ desiccated andthen weighed in an analytical balance $($mass $=4$ mg$).$When the same $20$ mL sample is filtered and the filtrate is kept in hot air oven, followed by desiccation, it weighed only $2\mathrm{.}75$ mg$.$This $2\mathrm{.}75$ mg of solid material when kept in a muffle furnace at $550\backslash$deg C for sufficient time, cooled and desiccated, it weighed $1\mathrm{.}15$ mg$.$ How much organic solids is present in the dissolved form?