Question

4 3/4-r=3 6/12

Answer 1

4 3/4 - r = 3 6/12
19/4 - r = 42/12
19/4 - 42/12 = r
57/12 - 42/12 = r
15/12 = r

check...
19/4 - r = 42/12
19/4 - 15/12 = 42/12
57/12 - 15/12 = 42/12
42/12 = 42/12 (correct)

answer : r = 15/12 or 1 1/4