1) 2 13/48 + 2 5/12 = 109/48 + 29/12 = 10948 + 116/48 = 225/48 = 75/16 = 4 11/16
2)4 11/16 : (- 3 3/4) = 75/16 : ( - 15/4) = 75/16 * ( - 4/15) = - 5/4 = - 1 1/4
3)9 3/4 : (- 13) = 39/4 ÷ (- 13) = 39/4 × ( - 1/13) = - 3/4
4)- 1 1/4 + ( - 3/4) = - 1 1/4 - 3/4 = - 5/4 - 3/4 = (-5 - 3)/4 = - 8/4 = - 2