The problem is simply asking us to convert the units from BTU to units of foot pound force. To do this, we use the conversion ratio 1 BTU/778.169 ft-lbf. We do as follows:
1500 BTU/hr ( 777.169 lbf-ft / 1 BTU ) = 1165753.5 lbf-ft/hr
Hope this answers the question.
