13 3/4 + x = 7 1/4
becomes x = 13 3/4 / 7 1/4
13 3/4 = 55/4
7 1/4 = 29/4
55/4 / 29/4 = 55/4 * 4/29 = 220/116
220/116 reduces to 1 26/29
