\frac{N}{S} = \frac{A}{S t} = \frac{Q}{S t} = \frac{c m (t_{2} - t_{1})}{S t} \approx 160 W / m^{2}

${\frac{N}{S} = \frac{A}{St} = \frac{Q}{St} = \frac{cm(t_2 -t_1)}{St} \approx {160}\,\mathrm{W/m^2}}$

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