I am stumped on this one, so simple yet....

a1=9:00
b1=9:30
c1= the time difference with the formula =B1-A1 (results =0:30)
d1=0:30 (used as a reference or goal)
e1 formula =IF(c1=D1,"Yes","No") In this case the answer is YES

Now the hard part, if I change the cells to:
b1=9:50, c1 showes 0:50
D1=0:50
e1 is now = NO it should be YES

I tried test values of 0:49 and 0:51 by changing b1 d1 they work and say
YES, only 0:50 minutes errors????

TX MIke