It is: 42/100 = 21/50 simplified
Yes, it can be simplified and the simplest form of 16 over 42 is 8 over 21.
4/21
42 over 26 can be simplified as 21 over 13
10/21
13/21
= 21/50
30/42 = 15/21 = 5/7
72/42 = 12/7
4 over 42. 2 over 21 cannot be simplified any further
13/14 + 5/6 = 39/42 + 35/42 = 74/42 = 37/21 or 116/21
You can take 21 out of both of those, leaving 2/11.