An input stream contains oil sands, comprising $14\mathrm{.}0\%$ oil, the remainder being solid sand particles. In the

initial stages of steady$-$state processing, the oil sands are mixed with warm water and pumped to a

settling tank. In this tank three layers are formed. The three layers are:

$1.$ Bottom layer containing $95\mathrm{.}0\%$ sand and $5\mathrm{.}00\%$ water

$2.$ Middle layer containing $5\mathrm{.}00\%$ oil and $95\mathrm{.}0\%$ water

$3.$ Top layer containing $70\mathrm{.}0\%$ oil and $30\mathrm{.}0\%$ water

The top layer is skimmed off and sent for further processing, while the bottom two layers are disposed

of$.$

How much warm water is added to $200$ tonnes of oil sands in this process if $85\mathrm{.}0\%$ of the total oil is

recovered in the top layer $(3$ sig. figs$)?$ All percentages given are weight percentages.