lnStart=15.30
lnStop =19.00
lnMin = (INT(lnStop) * 60 + (lnStop - INT(lnStop))*100) - ;
	(INT(lnStart) * 60 + (lnStart - INT(lnStart))*100)  
lnHours = ROUND(INT(lnMin /60) + (lnMin % 60)*.01,2)	

? lnMin, lnHours 
* or one-liner
? lnStop - lnStart - ;
	IIF((lnStop - INT(lnStop)) < (lnStart - INT(lnStart)), .40, 0)