Answer
$|Q_H| = 49368 J$ or $49.37 kJ$
Work Step by Step
$K_C = \frac{|Q_L|}{|Q_H| - |Q_L|}$
Solve for $Q_H$
$K_C(|Q_H| - |Q_L|) = |Q_L|$
$|Q_H| - |Q_L|) = \frac{|Q_L|}{K_C}$
$|Q_H| = \frac{|Q_L|}{K_C} + |Q_L| $
$|Q_H| = |Q_L| [\frac{1 + K_C}{K_C}]$
Where $K_C = 5.7$ and $Q_L = 42000 J$
$|Q_H| = 42000 J [\frac{1 + 5.7}{5.7}]$
$|Q_H| = 49368 J$ or $49.37 kJ$
