Ok so 7:12 is already in it's simplest form because there is nothing that can go into both 12 and 7 (which is a prime number). So in fraction form it would be 7/12
8:10, so a number than can go into both 8 and 10? 2 can go into 8 4 times, and 10 5 times. So the fraction would be 4/5 which is in simplest form (5 is prime)
25:50, again, what can go into both 25 and 50? 5 can. 5x5= 25 5x10=50. The fraction would be 5/10, which can be reduced to 1/2.
80:60, 10 can go into both of them. 8/6 which can be reduced to 4/3 (2 goes into 8 4 times and 2 goes into 6 3 times)
78:780, 2 can go into 78 32 times and can go into 780 390 times. 32/390 can be reduced to 16/195, which I believe is in it's simplest form (no number can go into both 16 or 195 evenly).
All the other ratios are solved similarly, so I think you can do it.
XD hopefully I explained it correctly, but you should also ask an adult to help you and/or correct your homework when you're done.
