Step-by-step explanation:
we can calculate total emitted power per square from Stefan-Boltzmann law
P = e σ AT⁴
where
P= power of body's thermal radiation
A= surface area of the body
σ= Stefan-Boltzmann constant it's value is

T= temperature of the body
e= emissivity of the substance here equal to 1
now by putting all the values in given formula

we get the answer
