 
<translate> Jimlar lambobi bakwai = 7X21 = 147 Jimlar lambobi 3 na farko da na karshe 3 = 3 X 19 + 3 X 23 = 126 Saboda haka, lambar tsakiya ita ce (147 - 126 ) = 21 Amsar ƙarshe: (E). <eng> The total of seven numbers = 7X21 = 147
The total of first 3 and last 3 numbers is = 3 X 19+3 X 23 = 126
So, the middle number is (147 - 126 ) = 21
The final answer: (E). 