FIrslty let's find the common denominator of 2 3/8 and 1/4:
2 3/8 = 19/8
1/4 = 2/8
Now we have to find out how many 2/8s will fit in one 19/8. To do that we can divide 19 by 2:
19/2 = 9,5
We can see that Dao will be able to make 9 humbergers, because he's still missing 1/8 of meat to do the 10th humberger..