Two black parallel rectangles are $0\mathrm{.}9$ m $\backslash$times $1\mathrm{.}5$ m and are $0\mathrm{.}3$ m apart. The two parallel rectangles are blackbody surfaces and radiant heat is transferred between them, and the upper rectangle receives a total of $53000$ W of radiant heat from the bottom rectangle. If the temperature of the upper rectangle is uniformly $15\backslash$deg C$,$ what is the temperature of the bottom rectangle?