The answer is 91公仔箱論壇' U; R9 ~1 A. [; s; z
1 row 3x4+1x3=15
! R5 {% i4 [. s4 z1 C+ q3 w公仔箱論壇2 row 4x5+2x4=28公仔箱論壇% F- d2 @4 a7 m* F& D6 N( ~! K
3 row 5x6+3x5=45, o, z# { q7 G2 Z( \" n. N# V
4 row 6x7+4x6=66, f6 ]$ e$ a1 r" x/ n6 j/ Y
5 row 7x8+5x7=91  |