A laundry can purchase soap containing $30\%$ water for a price of $$0\mathrm{.}3/$kg FOB the soap manufacturing plant

$($i$.$e$.$ at the soap plant before shipping costs, which are owned by the purchaser of the soap$)$ It can also

purchase a high grade of soap that contains small $\%$ water. The freight rate between the soap plant and the

laundry is $ $6\mathrm{.}05/100$kg$.$ If the high grade of soap is $$0\mathrm{.}45/$kg$,$ how much percentage of water could be in the

high grade of soap? $(15$ points$)$