Re-arrange suitably and find the sum in each of the following :
(i)1112+−173+112+−252
(ii)−67+−56+−49+−157
(iii)35+73+95+−1315+−73
(iv) 413+−58+−813+913
(v)23+−45+13+25
(vi) 18+512+27+712+97+−516
Find the product
(1) 4 ⊗5 3
(2) 5 ⊗7 8
(3) (4 ⊗11 3) ⊗11 7
(4) (5 ⊗12 2) ⊗12 6