Question

4 3/12 - r = 3 6/12

Answer 1

convert everything into regular fractions:
51/12 - r = 42/12

Answer 2

move r to the right and 42/12 to the left:
51/12 - 42/12 = r
(51-42)/12=r

Answer 3

r = 9/12 = 3/4