The answer is 91
5 z+ `$ }9 }% \- y2 b/ r1 row 3x4+1x3=15tvb now,tvbnow,bttvb6 F% ]! X5 W! z" U
2 row 4x5+2x4=28
9 z4 z+ y2 o6 ? R. \2 n9 o3 M# x公仔箱論壇3 row 5x6+3x5=459 ?9 j* n* W' `- J! E! W8 n
4 row 6x7+4x6=66tvb now,tvbnow,bttvb, i4 W& T0 f6 [( A7 M/ R; i- U2 ^
5 row 7x8+5x7=91  |