If the heat of combustion for a specific compound is -1110.0 kJ/mol and its molar mass is 89.45 g/mol, how many grams of this compound must you burn to release 834.20 kJ of heat?

$67.22 g$ of the substance must be burned to release that much heat.
$834.20 k J \left(\frac{m o l}{1110.0 k J}\right) \left(\frac{89.45 g}{m o l}\right) = 67.22 g$