3 5 x 7 9 3 5 x 2 9 July 8, 2019 16 32 64 128 3 5 x 7 phần 9 3 5 x 2 9 3 5 5 x 7 = 35 (3 9 + x) – 2 5 5 7 3 x-5=x+3 3 5 - - 9 7 3 x 3 = 9
