You find the common factors between 36 and 40. So they are bothe divisable by two so that turns them into 18 and 20. Then you can divide them both by 2 so that is 9 and 10 and that is the lowest you can go without decimals so that is the answer.
You cannot simplify 31 over 36 because 31 is prime.
you do
Yes
36/8 = 9/2
one over two
36/42
No
no
36/24=3/2
45/36 = 5/4
17/18
3/7