Hello there! The formula for dividing fraction is keep, change, flip. You keep the first fraction the same, change division into multiplication, and flip the second fraction over by its reciprocal. In this case, 5/12 remains the same, division becoems multiplication, and 20/36 flips over to become 36/20. So the expression becomes this:
5/12 * 36/20
Now, we multiply straight across. 5 * 36 is 180. 12 * 20 is 240. 180/240 is 3/4 in simplest form. There. The quotient is 3/4.